OBITUARY : Professor Peter Hilton

11 November 2010

OBITUARY : Professor Peter Hilton
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Professor Peter Hilton, who died on November 6 aged 87, played a key role 
in the secret wartime codebreaking agency at Bletchley Park and went on to 
become one of the most influential mathematicians of the postwar 
generation.

In 1941 Hilton was a young Oxford undergraduate when he was recruited to 
Bletchley to work in a section known as the Testery (after its head, a 
linguist called Major Ralph Tester). His colleagues there were Alan 
Turing; Roy Jenkins ( the future Labour Chancellor of the Exchequer ); 
Peter Benenson ( who later founded Amnesty International ); and Hugh 
Alexander, the British chess champion. Also there was Donald Michie, a 
young Oxford classics scholar who became a professor of artificial 
intelligence and whose various claims to fame included the post of curator 
of the Balliol Book of Bawdy Verse.

Hilton initially worked with Turing on breaking German naval codes 
produced by Enigma machines, and concentrated on top secret Offizier 
messages ( for officers' eyes only ). His extraordinary powers of 
visualisation meant that in his mind's eye he could unpick streams of 
characters from two separate teleprinters - a faculty that was to prove 
invaluable in the feverish mental chess game with the enemy.

Success rates were high and decryption was accomplished at remarkable 
speed. At the end of 1942 he was moved to work with a group of some 30 
mathematicians on the yet more sophisticated code which the Germans had 
started using in 1940 to encrypt top-secret messages – mainly between 
Hitler and his generals.

Known by the irreverent nickname "Fish", these messages to and from the 
German High Command were produced by a much larger and more complex 
machine than Enigma.

Many years after the war, this was revealed to be a Lorenz SZ40 encoder, 
but at the time staff at Bletchley Park called it "Tunny". Hilton played 
one of the most important roles in the unit's cryptology department, 
monitoring any changes in "Tunny's" output and eventually becoming chief 
cryptanalyst on the "Tunny" project.

Codebreakers managed to work out how "Tunny" was constructed as a 
consequence of an operational slip by a German cipher operator in 1941. It 
was a crucial error. As a result, Bletchley Park cryptanalysts led by 
Hilton were able to work out the basic design and build an emulator they 
called Heath Robinson, after the cartoonist famous for drawing crackpot 
inventions.

But this proved far too slow at processing the data, and eventually a 
bigger and better version was developed. Colossus, as it was known, was 
the world's first programmable computer, weighed a ton, and could crack a 
Lorenz-encrypted message in hours rather than days. Eventually, 10 were 
built.

Occasionally German encoders failed to change the settings on their 
machines and two messages would be sent under the same "key" - a vital 
lapse in security that was known at Bletchley as a "depth". From this, 
decoders were able to produce a stream of "clear" ( or deciphered text ), 
that was a jumble of the two messages mixed together.

Using his startling ability to visualise two teleprinter streams, Hilton 
spent countless hours resolving the merged "depths" into individual 
messages in "clear", deriving "enormous excitement" in cracking what 
appeared at first to be "utter gibberish".

"For me," he remembered, "the real excitement was this business of getting 
two texts out of one sequence of gibberish. I never met anything quite so 
exciting, especially since you knew that these were vital messages."

After the war Hilton was indignant about the treatment meted out to Turing 
- "an authentic genius" - who committed suicide in 1954 after his 
homosexuality was exposed. Hilton ( who renewed his acquaintance with 
Turing postwar at the Mathematics faculty at Manchester University ) never 
guessed Turing's sexual orientation in all the time they worked together, 
and neither did the Bletchley Park authorities. "Otherwise," as Hilton's 
fellow codebreaker Jack Good noted, Turing may have been driven to kill 
himself earlier and "we might have lost the war".

Peter John Hilton was born on April 7 1923 in Brondesbury, north London, 
the son of a GP with a practice in Peckham. From St Paul's School he won a 
scholarship to Queen's College, Oxford, where he read Mathematics and, 
like all undergraduates at the time, underwent military training, in his 
case for the Royal Artillery...../snip/


.....During his time at Bletchley Park, Hilton was given every fourth week 
off to hone his cryptanalytical skills; by way of a change of mental gear, 
he helped Turing solve chess problems, puffed on his pipe, and once spent 
a sleepless night composing one of the world's longest palindromes : DOC, 
NOTE : I DISSENT. A FAST NEVER PREVENTS A FATNESS. I DIET ON COD.

Peter Hilton married, in 1949, the actress Margaret Mostyn, who survives 
him with their two sons. 


http://www.telegraph.co.uk/news/obituaries/science-obituaries/8124447/Professor-Peter-Hilton.html