John Croft, a codebreaker at Bletchley Park during the Second World War who later became a highly regarded abstract artist, has died at the age of 103. His paintings were described by the art critic Brian Sewell as 'exquisitely judged, hard-edged abstracts'.
Early Life and Codebreaking at Bletchley Park
Born on 6 January 1923 in Brondesbury, north London, to Doris (nee Phillips) and Oswald Cohen, Croft was descended from Dutch Jewish immigrants. The family changed their surname to Croft in the late 1930s. He was educated at the Hall preparatory school in Hampstead and Westminster school before going to Christ Church, Oxford, where he studied history.
In 1942, his tutor asked if he might be interested in intelligence work. 'The prospect, whatever that involved, seemed enticing and I gratefully accepted the opportunity,' Croft later recalled. He was interviewed by Colonel John Tiltman, Bletchley Park's chief codebreaker, whom he described as 'almost the parody of a regular army officer, with toothbrush moustache and rather clipped speech'.
After training in basic codes and hand ciphers alongside other recruits, including future author Angus Wilson, Croft was assigned to the Testery, a section run by Ralph Tester. There, he worked on breaking the German Lorenz enciphered teleprinter system, codenamed Fish by Bletchley. The Lorenz ciphers were used on the highest security links between Berlin and German fronts, often carrying personal orders from Adolf Hitler.
Work on Soviet Ciphers and Encounter with Kim Philby
Croft later moved to Bletchley's diplomatic and commercial section in Mayfair, where he worked on Soviet cipher systems used to send secret messages to European communist parties and sympathisers. The section head, mathematician Bernard Scott, had broken into the messages using a substitution cipher based on an English edition of Shakespeare's plays. Croft and Scott spent a day searching the British Library shelves for the specific edition used to encipher the key, without success.
In 1944, traffic on the network increased rapidly, leading to the recruitment of three more codebreakers, including Ernst Fetterlein, Tsar Nicholas II's official codebreaker. Kim Philby, then head of a new counter-espionage section in MI6, received decoded messages and visited the section, meeting Croft. After Philby's visit, Fetterlein's locked cupboard was found forced open and papers disturbed. Croft believed Philby, later exposed as a Soviet double agent, was responsible.
Post-War Career and Artistic Pursuits
After the war, Croft returned to Oxford to finish his degree. He applied to join GCHQ but was refused, and an appeal to Foreign Secretary Ernest Bevin failed. He then considered a degree in art history at the Courtauld Institute, where he was interviewed by Anthony Blunt, later exposed as the 'fourth man'. When Croft said he had worked for 'a department of the Foreign Office', Blunt became 'remote and chilly'.
Croft earned a master's in sociology from LSE in 1953 and taught at North Hammersmith secondary school for boys before joining the Home Office. In 1972, he became head of the Home Office Research Unit, where one colleague was novelist PD James. He retired in 1981 and was appointed CBE in 1982.
Artistic Career and Later Life
While at the Home Office, Croft took up oil painting, focusing on 'non-figurative, minimalist work derived from landscape'. His paintings were included in group shows from the 1960s and were praised by Brian Sewell. He had solo exhibitions at the Gardner Arts Centre (now Attenborough Centre) at the University of Sussex in 1970 and at the University of Warwick in 1971.
After living in the Isle of Man, Croft moved to Bath with his partner, Ray Kelly, a former British Airways employee, who died in 1999. Croft died on 12 July 2026.
