Peter Frank George Twinn CBE (9 January 1916 – 29 October 2004[1]) was an English mathematician, Second World War codebreaker and entomologist.
He was the first mathematician to be recruited to GC&CS,[2] Head of Intelligence Service Knox (ISK) from 1943, the unit responsible for decrypting over 100,000 Abwehr communications.
[3] Born in Streatham, South London, Twinn was the son of a senior General Post Office official.
They offered me this job at the princely salary of, I think, £275 a year," he said, "which sounded all right to me, and I was taken along on the first day to be introduced to Dilly Knox."
He began as an assistant to Alfred Dilwyn ("Dilly") Knox, who headed a team of codebreakers at GC&CS.
An eccentric but brilliant character, Dilly Knox was the first British codebreaker to work on the Enigma cipher.
But, as war loomed, GC&CS began employing mathematicians, as well as chess players and crossword experts.
Twinn was the first British cryptographer to read a German military Enigma message, having obtained vital information from Polish cryptanalysts in July 1939.
The mansion in the park was used by the staff, but many other buildings had to be constructed to accommodate the large number of people who worked for GC&CS during the war.
In the meantime, Koch had set up a company with the hope of selling his encryption machine for commercial use; one disadvantage was that numbers had to be spelt out in words.
When an operator, enciphering a message, pressed a key, an electric current passed through the machine and the rotors turned mechanically, but not in unison.
Polish cryptologists, some of whom were brilliant, handed over to their British colleagues key information about Enigma, including replica machines.
The ability to read German encoded military messages was of inestimable help to the Allies in winning the war.
It was achieved largely because of the efforts of Twinn, Knox, Alan Turing (who later became the father of artificial intelligence) and others at Bletchley Park.
[5] Twinn's carried on government work after the war in a number of departments, including, in the late 1960s, as Director of Hovercraft in the Ministry for Technology.
Twinn became interested in entomology, gaining his doctorate from the University of London in the jumping mechanism of click beetles.
Twinn married Rosamund Case, whom he had met at Bletchley Park through his interest in music, in 1944; they had a son and three daughters.