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This is a British mathematician
called Bill Tutte.

You won't have heard of him.

But in 1943, he pulled off
what many believe

was the greatest intellectual feat
of World War Two.

It shortened the war
and saved millions of lives.

He died in 2002 without
ever being officially recognised

for his achievement.

This is a former GPO engineer
called Tommy Flowers.

In 1944, he turned Tutte's
mathematical ideas

into the world's first computer.

He died in 1998.

Chances are, you won't have
heard of him either.

Backed by the brightest talents
of Bletchley Park,

they allowed Britain
to break a top secret machine

employed by Hitler to dictate
the course of the war.

This machine was NOT Enigma.

It was something far more secret
and significant...

and you definitely
won't have heard of that.

It was Hitler's Blackberry really.

That intelligence probably shortened
the war by a couple of years.

They were the forgotten heroes
of Bletchley Park.

This is the story of a secret war
and how two men changed the world

and then disappeared from history.

This is Bletchley Park.

In 1939, it became the wartime
headquarters of MI6.

If you know anything about
what happened here,

it will be that a man
called Alan Turing

broke the German naval code known
as Enigma and saved the nation.

And he did...
but that's only half the story.

There were three heroes
of Bletchley Park.

The first is Alan Turing.

The second was Bill Tutte
who broke the Tunny system,

a quite amazing feat.

And the third was Tommy Flowers,

who, with no guidelines,
built the first computer ever.

Amazingly, the story of Tutte and
Flowers has never been fully told -

but then again, Bletchley
is Britain's fortress of secrets.

The secrecy about Tunny and Colossus

has completely distorted
the history of computing

and it's also left the story

of the World War Two
codebreaking effort incomplete.

It's like there's not enough
room on the stage

because the Enigma story
has taken up so much space.

It's not surprising
that there are stories

still to be told about this place.

Bletchley Park was
Churchill's house of secrets.

It didn't even appear on any map.

Nicknamed "Station X",
this sprawling complex was home

to a clandestine army engaged
in a shadowy struggle

for military intelligence.

Bletchley Park's codebreaking
history began in 1939,

with a tiny attic radio station
hidden at the top of the house.

It would eventually give its name
to the entire estate.

Station X.

As the war progressed, operations
expanded out from the main house

to a haphazard collection
of huts and concrete blocks.

Here, some of the most brilliant
minds in the country

were involved in a constant battle
to learn the enemy's secrets.

Arguably, the toughest
and most rewarding struggle

was against a code called "Tunny".

In defeating it,
Bill Tutte and Tommy Flowers

would change the world.

Captain Jerry Roberts
worked alongside Bill

and was involved
in the attack on Tunny.

He is the last surviving
codebreaker from an elite group

known as "The Testery".

Now aged 90, this is the first time
he has visited this part of the Park

since the war.

General Eisenhower
said Tunny decrypts

shortened the war
by at least two years.

In its heyday, the place
was really buzzing.

Thousands of people
working here, hard.

Very disappointing
to see it in this shape.

The Testery were backed
by a huge team of people

processing the information
gained from the broken codes.

And while much of Bletchley
has been restored,

the places that housed
those workers are abandoned.

The secrets they uncovered, though,
are still coming to light.

World War Two was a conflict
uniquely designed

to create secret messages
and exploit them.

The rapidity and mobility of armies
during the Second World War

meant that you couldn't
get your fixed-line communications,

which are much more secure,
up quickly enough.

So increasingly, they came to rely
upon radio technology

and radio technology, of course,
is broadcast to the world

and they would, therefore,
be able to intercept it.

It's a considerable weakness.

If you could break into
the right encoding system

then you could deliver victory.

That was what Bletchley was built
to do and their most secret

and stunning success came against
a code which they nicknamed "Tunny"

and the Germans called "Lorenz".

Its existence
was a tightly guarded secret.

Even now it's not common knowledge.

Tunny was generated by
a new top-secret machine,

a device Hitler called
his "Geheimschreiber" -

"The secrets writer".

To understand its genesis
and the need for this super code,

you first have to look at
the system that preceded it.

Enigma.

Enigma would dominate
the early work of the codebreakers

of Bletchley Park,
and it was a formidable opponent.

Well, this is an Enigma machine,
a type of cipher machine

that was used throughout
the Second World War by the Germans.

Throughout the Second World War,
they believed that the ciphers

that were made on this machine
could not be broken.

If I press the key for letter "N",
lamp "W" lights up on this occasion.

So "N" would be enciphered into "W".

If I release my finger and press "N"
a second time, on this occasion,

lamp "M" lights up,
and the reason for that

is the rotors at the back
of the machine have moved

each time I press a key
and that changes the internal wiring.

Enigma masked Germany's
wireless traffic.

The Morse code transmissions
that were monitored back
in Britain by "Y Stations",

monitoring and recording stations,

operated almost exclusively
by women.

From the First World War, there was
considerable emphasis put on

the quality of wireless receivers.

You might think that the most
important thing in wireless

is the transmitter or the medium, the
ether through which messages travel,

but for the cryptographers,

the main thing was the quality
of the receiver,

being able to pick up the last
lingering trace of a message,

and that was where
the British radio engineers

were considerably more advanced
than their German counterparts,

and the Germans simply
didn't believe that their messages

could be picked up
as far away as they were.

They didn't believe that messages
from Russia, for example,

could be picked up in Britain.

For the first years of the war
those listening posts

were dedicated
to picking up Enigma traffic.

Then, in 1941,
a new and strange sound

began to be picked out
from the ether.

"A new kind of music",
it was described as

by the British listeners
when they first heard it.

This strange music was a new coding
machine delivering messages

not by Morse, but by teleprinter.

The information war was about to
move into new territory.

The advent of machine-made codes
had one immediate effect

on Bletchley Park -

they began to recruit
mathematicians.

Mathematicians were regarded as
weird, incomprehensible people

and it just wasn't really
understood what contribution

they could make to code-breaking.

These machine ciphers that were
introduced, Enigma and so on,

and there were others as well,

are incredibly
complex mathematically.

I mean, the First World War,

the British code-breakers
were wordsmiths,

people who translated
ancient documents for example,

cos it was all about words,

but in the Second World War
it was much more about mathematics.

The mathematicians were thrown
into the front line

against this new mystery system.

Even though the Nazis
believed Enigma was unbreakable,

Hitler demanded more security.

His style of command called for
a new and more direct

communications network.
It would carry more information

and supersede the tangle of Morse
traffic which his forces generated.

Enigma was really
out of date technology

by the time the war started.

Three operators were required

and then another three operators
at the receiving end.

There'd be the guy who
actually typed the message,

the operator would have an assistant
who would painstakingly note down

the letters as they lit up,

and then that would be handed over
to a radio operator

who would translate that
into the "dit-dit-da" of Morse code.

BEEPING

And then the process was
reversed at the other end.

So you had six people co-operating
in the transmission

of a single message with Enigma.
Very slow, very clumsy.

So the vast volumes of information
needed to fight a modern war

at that time would simply
have overwhelmed a system

based upon using an Enigma machine,
so they needed something which would

cope with the throughput
of information required.

And this is it.
The machine Hitler had dreamed of.

The Lorenz SZ40.

Or as the Allies called it, "Tunny".

This is an example,
quite a rare example,

of what is called a Lorenz
enciphering attachment.

Quite a complicated machine.

If I lift up the cover
and show you the interior.

If you count up, you'll find that
this device has got 12 wheels in it.

The Lorenz was much more
sophisticated than Enigma.

The operator at one end
typed in plaintext

and the operator at the other end
received the plaintext

on his teleprinter without
any intervention on his part.

The way in which this Lorenz cipher
machine worked was it would apply

two layers, two keys,
to your message,

so it wouldn't encipher it once,
it would encipher it twice.

The first encipher used five wheels.

Then they would apply a second key

and this used similar five wheels
and they had another two wheels

that were called, what we called
"stutters" in the key.

And then that would generate
a repeat character

and this was in order to try

and introduce this apparent
randomness into the key.

The 12 wheels made the machine
an awesome generator of code

and the number of potential
ciphering possibilities

multiplied out as...

which equalled 1.6 million billion
combinations.

Another innovation saw the Lorenz

incorporate the natural code of the
teleprinter into its basic design.

It's kind of modern
binary code really.

It's zeroes and ones and they just
took the teleprinter code

and they encrypted that.

With the Lorenz enciphering device,
the plain text letter "A"

was changed by a machine
which actually added to it

a pseudo-random character,
for example, the letter "K"

might have been used, for which
the teleprinter code was this -

four crosses and a dot and these
two characters were then combined

together by a process which
is sometimes called "addition".

If the two elements were the same
then the result was always a dot.

But if they were different,
the answer was a cross.

And here, they're the same
so it's a dot.

And if you looked at that set
of impulses in terms of

the standard international
teleprinter code,

you would find that that was,
in fact, the letter "N".

The letter "A"
has been enciphered to "N"

by adding
this random character "K" to it.

Now, at the receiving station,
of course,

the letter "N" is the cipher message

and we already know that that's going
to come in, in terms of this pattern.

And now, a little bit of magic...

If at the receiving station the same
random character that was used

by the sender was combined
with it, in the same way...

Adding up... Two, these are different
so the result's a cross.

They're different,
the result's a cross. Same, a dot.

These two are the same, a dot.
And these two are the same, a dot.

The result would be that.
And if we look back,

that of course
is the old character "A"

which was the original plaintext.

The actual number of teleprinters
using this code

in the new network
was less than 30.

But they were the lifeblood
of the German command,

feeding out
to the furthest fingertips

of the Third Reich's reach.

More importantly,

as many of the generals needed
information about other campaigns

as well as their own, one line
of traffic could produce an insight

into the entire German war effort.

This was the prize
awaiting the codebreakers.

To get to it, they had to crack
a code no-one understood,

produced by a machine
no-one had seen,

and with a range
of possible encryptions

that were utterly unimaginable.

To defeat the impossible machine,
Bletchley would turn to

a 24-year-old mathematician
called Bill Tutte.

Bill was born in Newmarket in 1917,
the son of a gardener

at Fitzroy House,
a local racing stable.

As a child, his keen intelligence
soon showed itself.

He gained a scholarship
to Cambridge and County High School.

After winning the scholarship,
Uncle Bill faced

the even greater feat of getting
to and from the school,

which was roughly
a 12-mile journey there

and then 12 miles back again.

So he definitely had
a lot of determination.

At his new school he excelled,

winning prizes in every subject.

I imagine he might have been
frustrated at the school itself

in that he was apparently so much
ahead of all the other pupils

so he would've been a bit isolated
in that respect, I imagine.

In 1935, he went to
Trinity College, Cambridge

where he studied chemistry
and then mathematics.

Bletchley's habit of raiding
the best academic talent

meant that Bill was sent to the Park
in 1941,

although not everyone
recognised his potential.

He first was interviewed
by Alan Turing

and was not chosen
to work on the Enigma project.

However, that was the best thing
that could have happened to Bill.

Instead, he was chosen
by John Tiltman

to be part of the research group.

They were the cream of
the cryptographic people.

Bill found himself in the right
place at the right time.

After months of fruitless
examination,

the team working
on the invincible Tunny code

were about to be gifted a way in.

At the beginning,
the Germans were very sloppy.

They obviously had
so much confidence in the machine,

they were over-confident.

In fact, this is how
we came to break the system.

You need depth to break any cipher.

By depth, I mean a number of
messages sent using the same key

or the same system.

30th August, 1941.

A German operator had a long message
of 4,000 characters

to be sent from Athens to Vienna.

What happened is
they sent the message

and the person at the end said,
"Well, I didn't quite get that.

"Can you send it again?"

The German operator
went and sent it again,

but he didn't change
the wheel settings,

and so we got
what we called the depth,

two messages
with exactly the same encryption.

So he sends the same message

on the same setting,

and the trouble is then
that when he resends it,

he makes slight differences
in the punctuation,

so the message
isn't quite the same as it was.

He abbreviated Nummer, the German
word for "number", to "Nr",

so he didn't have to type in
the U-M-M-E every time,

and anything he could abbreviate,
he'd abbreviate it.

An intercept station
picked up these messages.

They realised
that they were radio teleprinter.

The message was sent to Bletchley
via a despatch rider.

When it got there,

the first person to attack it was
legendary codebreaker John Tiltman.

A former frontline soldier
in World War One,

Tiltman was awarded
the Military Cross.

But it was his talent for languages

that saw him rise through the ranks
in intelligence work.

He's generally recognised

as one of Britain's
best codebreakers
in the Second World war.

He did achieve quite a lot
on Japanese codes, for example.

He taught himself Japanese
in just a few weeks.

But he looked at this Lorenz cipher
and he was the first to realise

that there was a method of
breaking through this code.

The Lorenz machine
had a particular weakness.

If two messages were sent
with the same key sequence,

then there was a way in which
the signals could be recovered.

Let me show you.

We had a message earlier
where the plaintext was letter A

and the pseudo-random character
generated by the machine was K,

and the result turned out to be
the letter N.

Now, suppose another plaintext
message B was sent

using the same key.

Then on this occasion the answer
to that in fact turns out to be P.

I'm not going to show that,

but it's the same procedure
as we used before.

Now, we saw previously

that if you add K to this message
you recover the plaintext.

Suppose you add those up,

so that on the left-hand side
you've got A + B + K + K.

Now, the elements of those two
in each case will be identical,

they'll cancel each other out,

and in effect the K disappears
from the equation.

And of course, on the right-hand side
we've got N + P.

N + P, from the teleprinter code,
is in fact the letter G.

And so we can say
that this is what we've got.

We've got G, the sum
of the two pieces of cipher text,

and the question is,
is it possible to decompose that

back into the original messages,
which were of course A and B?

That was what we would like to do.

Well, there's no mathematical way
of doing it,

but one way in which it CAN be done

is to make an inspired guess
for one of those answers.

Suppose, for example,
we made a lucky guess

that the first message
was just the letter A.

Then if you take the G we've got
and add A to it,

then from the teleprinter code,
if you add G and A together

you discover that you do get B,
the second one.

And so if this make sense, that
makes sense, and you've got a result.

A second, more convincing example,
perhaps, is this one,

which is based upon six letters.

..is the sum of,
in teleprinter world,

the names of two principal cities
in the United Kingdom.

Now, the question is,
could we resolve that

into the actual names
of these cities?

And the method they used
at Bletchley was based upon

intuition and perseverance.

For example, if you've got
two important towns here,

it's conceivable that one of them
might well be London.

And so a good try...

And then proceed to add these
pairs of letters together

using the teleprinter code method
I showed you earlier.

We won't do those.
It'll take us too long.

But I assure you that if you do,
you come up with this result.

Now, it might be argued that
that could have occurred by chance,

but it's very unlikely,

and so this approach was one
that was used at Bletchley Park

to decompose these combined messages.

Colonel John Tiltman
would take such a message

and he would use
a plausible piece of German,

something he thought might well occur
at the beginning of
one of the messages,

add it into the composite

and see if something in plausible
Germanic came out as a result.

Tiltman took ten days to hand-break
and unravel the transmission.

In his extraordinary feat,
he manages to extract from this

the cipher text,

what was the cipher text,
what was added to the plaintext.

It was a phenomenal
piece of decryption.

But it still didn't help
the team understand

how they could regularly read Tunny.

He couldn't work out the system -

how the machine worked,

and the job was passed
to Bill Tutte.

Tutte sort of recalls it
as almost an act of desperation -

"Oh, well, we can't work it out -
here you are, you have a go at it,"

almost disparagingly, you know?

And Tutte sits down
and he sees patterns.

He's looking for patterns.

And he did put this 4,000-word
message into columns

and made a rectangle out of it,

and he thought about what might be
a useful length of this.

And then he noticed that
there were certain repetitions

that went across the rectangle.

He realises that there seems to be a
pattern every 23 times, a rotation.

He thinks it might be 25,
so he tries multiplying 23 by 25

to see if the pattern
extends along that.

And it doesn't quite work,

but the pattern does extend
along 574.

So he thinks then,

"Ah, well, maybe it's 41,"

because 41 is a prime number of 574.

You wouldn't have a machine
that rotated through 574 positions.

"Maybe it's 41."
And he tried it, and it worked.

From that, he began to deduce,

"Well, this starts repeating itself
after 41 strokes,"

that you get a certain resonance

that even though
it's affected by other impulses,

the dominant thing is here the fact
that you get this resonance after 41.

So he says, "Well, I think the
first wheel in this has 41 spokes."

Then he starts working on
the second wheel, and so forth.

I was working in the same office
as Bill Tutte for most of that time,

and I can still remember him
staring into the middle distance

and making counts
on reams and reams of paper.

And I used to wonder whether
he was actually doing anything!

My word, he was!
The most extraordinary achievement.

Using Tutte's insight
and a method known as Turingery,

the Testery applied brute
mental force to break the code.

As they did, it became apparent

just what a valuable source of
information Tunny would prove to be.

We saw the signatories and we saw
who the messages were sent to.

So we were well aware of all that.

And they included

Field Marshal Keitel, who was
the head of the whole German army,

which was not a bad start,

and Jodl, who was the Chief
of Staff of the German army,

in other words
the chief operating officer,

and his number two, Warlimont.

But in 1944 they were joined
by a fourth -

Adolf Hitler himself.

You're almost in
the High Command meeting,

where they're working it all out.
You are almost actually
the fly on the wall.

The world's toughest code
had been broken.

Hitler's secrets were laid bare,

and the course of the war
was about to change,

all because of
one sloppy, lazy error

by a lowly teleprinter operator.

I think this German operator
did us such a huge favour,

I think there ought to be
a statue of him in Whitehall.

The first chance for Bletchley Park
to use Tunny information
in the field

came at the battle of Kursk
on the eastern front.

The Testery, the elite group
commanded by Major Ralph Tester,

were still breaking
this impenetrable code by hand.

Even so, they had uncovered
an incredible amount of information

regarding plans for
a massive surge by Germany

against the Russian forces.

The Tunny decrypt showed
that they were about to make

a major assault
on the Russian lines,

and we were able to warn
the Russians.

But much more than that,

we were able to tell them
how the attack was planned.

"It's going to be
a pincer attack."

And even more astonishingly,

we were able to give them
the whole order of battle.

It was the Nazis' last chance to put
the Red Army on the back foot,

but the Russians, forewarned and
forearmed, were waiting for them.

Kursk was both the largest
armoured clash in history

and the single bloodiest day
of aerial warfare ever.

By the end of it, Germany's
Russian campaign was in tatters

and the Red Army gained
an initiative they would press
all the way to Berlin.

The Russians, of course, called
Kursk "the turning of the tide".

Kursk proved just how important
intercepted Tunny messages could be.

The challenge now was to accelerate
the decoding process.

I've got a page up here
that mentions Bill Tutte.

It says that he invented
what they call...

the "1 + 2 break-in method
was invented by William Tutte
in November 1942."

What Bill did,
his first achievement was

he actually diagnosed the machine,
the structure of the machine

and how the cipher worked,
purely from intercepted messages.

Nobody had actually
seen the machine at all.

But then, his second
major contribution

was working out a statistical method
of cracking the machine.

The hand methods that they had used
up until then were no longer possible

because of extra German
security measures and so on,

so they were coming to an end
of what they could do
in cracking these messages.

And then Tutte worked out
this method.

It was a mathematical
and statistical attack
on the coded messages,

and it required a huge amount
of checking and counting of data.

Luckily, at Bletchley Park
there was a man who had an idea

how this work could be done.

Putting Bill Tutte's theories
into practice

led to one of the
great technological breakthroughs

of the Second World War,

a breakthrough kept secret
for nearly 60 years.

It was made by a GPO engineer
called Tommy Flowers.

Flowers was a brilliant man.

He was quiet,
he had a slightly hesitant manner.

He looked very boyish,

and with his hair perpetually
smarmed back with Brilliantine,

he didn't look like someone
who was about to change the world.

But change the world he did.

Tommy Flowers was born
in Poplar, London in 1905,

the son of a bricklayer.

He was born into

a Cockney-speaking world,

and Flowers kept his accent,
to a greater or lesser degree,

right through his life,

and he said later in life

that his Cockney accent
had probably been a handicap to him.

His brilliant mind enabled him

to move out of that world
into a quite different world.

Like Tutte,
he was a scholarship boy,

but he would gravitate to industry
rather than university.

First, he did an apprenticeship
in mechanical engineering

before gaining a degree
at night school

and rounding off his education
at Dollis Hill,

the Post Office's unique
research laboratory in London.

Bletchley used the
Dollis Hill engineers to
help with their attempts

to harness machines
to the task of codebreaking.

This is how Tommy came on to
the radar of a pivotal
figure at the park,

the mathematician Max Newman.

He discovered
that you could mechanise

Tutte's method of
breaking this cipher.

He understood that it was something
that you could put into a machine.

Max's department,
called the Newmanry,

had built a machine
to crack Tunny.

Nicknamed Heath Robinson,
it kept breaking down.

Newman brought in Flowers
to fix the Robinson,

but Tommy had a better idea.

Tommy Flowers took one look at this
and said, "I can do that better."

I can have the patterns generated
in electronic circuits,

and now I've only got one tape, which
is the source tape, the cipher text.

I can read that now at 5,000
characters per second,

compared with 1,000
on Heath Robinson.

And I can now generate these patterns
in electronic circuits.

But, of course, that meant
that he had to have

vast numbers of valve tubes
in order to do this.

Valves were flaky kind of devices,

and the more of them that you had,
the greater the probability

that a couple of them would be
out of action at any time.

But Tommy's practical experience
meant that at that time,

he knew more about the potential of
this technology

than anyone else in the country.

He knew that if you left electronic
valves running for a long time

then you didn't get problems
with them.

The problems arose if you kept
switching them on and off.

Flowers knew he was right,

so he just went back to
his laboratory at Dollis Hill

and quietly got on with building
the electronic machine

that he knew
the codebreakers needed.

It was massive, the effort
that was required to do it.

Flowers told me that he and his group
worked until their eyes dropped out.

Eventually, he produces this thing
and they try it out,

and it works first time.

"Oh, gosh, that's luck."
So they try it out again.

And it works second time,
and it keeps working,

every time they try it out.
And they're so...you know,

"Good grief!" And he produces
this thing called Colossus,

which is the world's
first semi-programmable
electronic computer.

This is Colossus.

And what it did was, you took
the intercepted cipher text,

on a lot of paper tape.

Five bit code there. And that is
received by us on our radio station,

planked on a paper tape,

and loaded on to this part of
Colossus here, called the bedstick.

That's the part of Colossus
that holds the intercepted

cipher signal, and that is
joined into a loop,

and being read continuously.

And that is being read
at 5,000 characters per second.

That's the data going into Colossus.

They put the results of those
readings up on to a lamp panel here,

and here are the results
of a particular run.

So this is refreshed every time the
tape goes round one continuous cycle.

We got one document that was written
at the end of the war.

A Technical Description
of Colossus 1.

It's a sort of technical manual
that describes

the different types of valves
that were used, for example.

And the different parts
of the machine,

the circuit diagrams of the valves

that were used in the different
parts of the machinery.

Internal bitstream generators,
the clock pulse system
and what have you.

Which were all, nowadays are
standard parts of any computer,

but all had to be invented
for this machine from scratch.

Now, as I say, they have
been taken over and used in
modern day computers.

As innovative as it was,
Colossus would only break
the two chi wheels.

Decoding Tunny
would still be a team effort.

There were seven stages
to the breaking of Tunny.

And, uh, whilst the Newmanry
was established,

the Newmanry handled two of them,

and then the Testery
handled the other five.

PHONE RINGS

Bletchley Park's scepticism
was immediately cured

as soon as they sa2
Colossus working.

They wanted more machines.

A little unrealistically,
they asked for four more Colossi

by the 1st June,
the projected date for D-Day.

As it was, Tommy and his team

only just managed to deliver
one more machine, the Mark II.

It was 1am on the 1st June,

and Flowers and his men just had to
go home to catch some sleep.

Flowers left one of his
right-hand men, Bill Chandler,

to carry on the fight alone, through
the small hours of the morning.

It was a very tough night for
Chandler. He worked on, and about 3am

he noticed that his feet
were in a pool of water.

A radiator pipe on the wall had burst

and water was inching
inexorably across the floor

towards high-voltage equipment.

It was quite dangerous, I think,
for Chandler, but he carried on

and eventually,
in the wee small hours,

he tracked down the fault

and he made some adjustments
using his soldering iron,

and Flowers turned up
a few hours later to find

Colossus working perfectly.

No one had managed to fix
the leaking radiator pipe, though,

and the people operating Colossus
had to wear Wellington boots

to insulate themselves.

But, Flowers beat the deadline.

It was the 1st June
and Colossus was working.

And so both Colossus I and
Colossus II were in operation

in time for the D-Day landings.

Tunny decrypts
made two major contributions
to the success of D-Day.

The first was to uncover
the entire defensive structure

of the German army.

The most important information

that Lorenz provided
for the run-up to D-Day

was the order of battle information,

which give details of the aircraft,
the tanks and so on

that were available to the Germans
against the D-Day forces.

None of this information
came from Enigma intercept.

Even got details of
aircraft being refitted

or moved around and so on.

So we had as much information
about the German air force

as the German air force itself had.

The other contribution
was to eavesdrop

on conversations which confirmed

that the Nazis had fallen
for Operation Fortitude,

the fake invasion of Calais.

Hitler had swallowed
our deception campaigns,

Hitler was convinced the attack was
coming across the Straits of Dover,

and that Normandy was a feint.

These generals, being professionals,

wanted it to be in
the Normandy region.

Hitler won out, so we knew that
the Normandy region

was less well-defended
than it could have been.

As the war through Europe
progressed,

the information
gained from the Tunny system

began to be used in
a more subtle and innovative way.

The effect of this flow
of information

helped us to "read" Hitler,

and predict the way
he would react and wage war.

In modern terms, it helped us
to get inside his head,

something which up until then
had been difficult to do,

because Hitler didn't act like
a normal military commander.

They had to learn not to think that
Hitler would do what they would do,

but to understand how Hitler would
actually react in these situations,

and do things that they simply
didn't expect him to do.

To hang on to territory when it was
completely pointless.

And this was one of the amazing
things about the war in Italy,

which people don't really get
or understand.

Once the British know
from this teleprinter link

that the Germans have decided
to keep the front going,

not only do they know how to
shape the immediate battle,

but they also realise
that they can keep the thing going

for as long as they like.

They can control the extent
to which the battle moves forward.

And by doing so,
can drain away German resources,

which won't then be used for the
main battle, the invasion of Europe.

This is the great irony
of the Nazis' love affair

with secrets and machines.

The very devices they trusted
to give them total security

allowed the Allies to play Hitler
like a fish on a line.

From the beginning, the Nazis
were in the impossible position

of having to trust these machines.

Machines which would prove
to be an Achilles heel.

The Nazi philosophy led them
to distrust people

and to put their trust in machines,

and the problem then is
you have to accept the idea

that the machine cannot be broken.

And in fact, all of these machines
are vulnerable

provided you approach it
in the right way

and that is what the British did.

And the secrets of Nazi Germany,
of Hitler himself,

flowed forth because of that.

Unlike here in Britain, where we had
one codebreaking organisation,

in Germany, there were seven
different organisations

involved in codebreaking.

And they spent a lot of their time
just fighting one another -

even, on one occasion, actually
physically fighting on the street.

So it couldn't bring together
a mass of people

and get the best out of them in
the way in which we did in Britain.

Similarly, their ideology meant
they were equally ill-equipped

to create their own version
of Bletchley Park.

Some people say
it's because the kind of people

that worked at Bletchley Park

were just, by German lights,
unemployable.

There were gays like Turing,
there were Jews,

there were totally
disorganised academics,

people who were brilliant
but practically dysfunctional.

They just did not fit
into the Nazi ethos.

By May 1945,
the war in Europe was over,

and Bletchley Park had done its job.

The war cost, on average,
ten million lives a year.

This is not counting the wounded
and the maimed.

Breaking Tunny at that juncture
was pretty jolly important.

For Tutte,
and for Flowers in particular,

peacetime would bring
a unique set of difficulties.

During the war, Bletchley operated
behind a wall of silence.

And thanks to
the nature of their work,

that secrecy would remain intact
for a long time to come.

Even once the war was over,
they still couldn't say.

That was a big issue, and the bosses
at the time understood

that that was a security threat,
if you like,

so they moved quickly
to say to people,

"Sorry, you've got to keep
this secret permanently, forever.

"You can't go home and tell
your mother or your father

"what you were doing."

And there are many interesting
and quite tragic stories

where people didn't,
and right into the 1970s and beyond,

parents died without knowing
what their children had done.

As for the machine itself, after
the war, Churchill let it be known

that Colossus had been
broken into pieces.

This was not true.

At least two survived and were taken
to the new GCHQ building,

where they were used
until the 1960s.

It seems very likely to me that
the Russians were using Tunny

in the Cold War period.

As the Russian armies
swept across Europe,

they captured numerous
German Tunny machines,

and they very probably
reconditioned them

and used them
for their own communications.

As the Tunny brick was being buried,
Tommy was recalled to Dollis Hill.

While he was there, the Americans
announced that they had built

the world's first computer,
ENIAC, in February 1946.

Already, the true history
of computing was being corrupted.

Tommy's suffering in silence was
slowly disappearing from history.

As for Bill Tutte, he was awarded
a fellowship at Cambridge,

before moving to Canada,
where he took up a teaching post

and met his wife, Dorothea.

Bizarrely for a man who had helped
defeat the Nazis

with the use of cutting-edge
technology,

Bill settled in rural Montrose,

surrounded by German-speaking
Amish farmers.

There, he continued to do
breakthrough work

at the University of Waterloo,

in a branch of mathematics
that was growing in importance

thanks to the rise
of computer science.

So he was working in an area
of mathematics

that wasn't especially fashionable
in the middle of the 20th century,

but it is the mathematics
that underlies

much of the theory of computation.

So the importance of his work
in the field he helped nurture

became astronomically important,

as the information age unfolded
in the late 20th century.

Well, all that was rather nice,

and you see it meant that
in the case of unit resistances,

all these determinants
were integers,

and therefore if you made
the horizontal side
equal to the complexity,

all your little squares
and rectangle sides,

they all became integers.

Certainly, we're talking about
a genius, yes, in many respects.

I think for what he did at Bletchley,
he proved it,

and for what he did in graph theory

and related parts of mathematics,
he proved it again.

Meanwhile, the story of Colossus
was beginning to creep out.

Tommy at last began to receive
some recognition.

In 1982, he was invited to talk

at the Museum of Digital Technology
in Boston.

When the hostilities commenced
in Europe in 1939,

all civil work in Britain had to be
subordinated to war work.

In the course of which
I was sent to Bletchley Park,

a highly secret establishment
some 50 miles north of London,

to take on some top-secret work.

He was still consulting with the MoD
as to what he could and couldn't say

and some things were restricted
even in the 1980s.

For Tommy, 12 years older than Bill,

the gradual lifting of secrecy
came too late.

Although he did live long enough
to see his famous machine
rebuilt at Bletchley.

He knew that history
had treated him badly.

I had the sense that
he was weighed down

by all those might-have-beens,

how fabulous it could have been
if things had gone differently.

If only it hadn't been
for the secrecy.

He also knew - and told me -

that the story was coming out
too late for him.

It was too late to make
any real difference.

Back in Canada, Bill took
the opportunity provided by

his 80th birthday lecture to
finally break his silence on Tunny.

And then, if you know
the wheel patterns...

INDISTINCT

..you can try the first chi wheel

against the first impulse...

He said that
when he finally did tell about it,

finally did speak of it,
then it lifted an enormous burden,

and it's hard to exactly say

to the extent to which it may have
altered his personality,

the personality that
I first met him as.

Outside of a select group
of academics, however,

few people realise the significance
of these men's achievements.

Bill received the Order of Canada
for his academic work,

but he was never decorated
by his own country.

He did, however,
gain the most important award
he could have wished for.

To become
a Fellow of the Royal Society

and to sign this charter book,
you need to be a leading scientist,

you need to convince your peers
that your work is good enough.

So you are refereed in the same way
that a scientific paper is refereed.

If you cross that hurdle,
Council of the Royal Society

will assess you as being
a good enough scientist,

you become a Fellow,
and if you get over that hurdle,

then you become
a Fellow of the Royal Society

and you sign this very fine book.

It helps if you have a Nobel Prize
tucked away somewhere.

In 1987, Bill signed the book.

He joined an illustrious group.

Isaac Newton,

Charles Darwin,
Winston Churchill,

and William T Tutte.

Other names in the book
are Alan Turing and Max Newman.

Tommy's name
was never entered in it,

although one of his many awards

does show the effect of
the revolution he helped begin.

When personal computers came in

in the 1980s and '90s,
he bought a PC,

tried to work out how to use it
and had difficulty,

so he enrolled
on a course at the local college

to learn
basic information processing,

and he got a certificate, here,

which shows that he passed
an introductory course

in information processing,

so he learned how to use programs
on a PC like everyone else,

and that was 28th June 1993,
when he was 87 years old.

Tommy's only public recognition
was to have a road

and an IT centre named after him
in his native East End.

The centre has since been closed.

At the end of the war,

Flowers got a leading inventors
award for his war work,

and this carried a monetary reward
of �1,000,

which was quite a lot of money
in those days, of course,

but Flowers being Flowers,

he shared it with his men, and
so by the time he had done that,

he'd got about 350 quid
for inventing the first
electronic computer.

Tommy died aged 92 in 1998.

And Bill four years later, aged 84.

Bill Tutte's memorial

is a simple headstone
in a rural Canadian cemetery,

and a lifetime
of academic achievement.

Tommy's is slightly different.

My father was cremated and the ashes
scattered in the crematorium,

but I think he would have recognised
that his main memorial

is at Bletchley Park
in the reconstituted Colossus.

As an engineer,
to have a working machine

as your memorial is the ideal thing,
really.

Hitler ordered this machine himself.

It should never, ever
have been broken.

But the minds at Bletchley Park

managed to find ways of breaking it.

And this is an amazing triumph
of mind over machines.

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