guardian.co.uk, Monday 8 February 2010 18.41 GMT
Author, academic and wartime intelligence officer at Bletchley Park
Peter Calvocoressi in 1942. He was seconded to the Nuremberg war trials in 1945.
Peter Calvocoressi, who has died aged 97, was best known as an Ultra intelligence analyst at the Bletchley Park codebreaking centre in Buckinghamshire during the second world war, but this episode represented only four years in a long career with many different aspects. International affairs was an abiding interest. By his 96th birthday he had published his 20th book, the ninth edition of his World Politics Since 1945. Its 845 pages were a tribute to his lifelong energy, formidable memory and powers of analysis. Yet author and historian were only two of his job descriptions. He had been a barrister, a publisher, an academic and a journalist and, after Bletchley, he had assisted the prosecution at the Nuremberg war crimes trials.
He was born in Karachi, now in Pakistan. His parents were Greek (hailing from the Greek island of Chios, off the Turkish coast) and Peter's father was a merchant in the family business. When he was three months old, they moved to Liverpool, and he grew up in a community of prosperous, English-speaking Greek families.
In 1926 he sat the Eton scholarship examinations and was placed second – making him possibly the only Etonian with two great-grandfathers who had been slaves. He maintained that his education turned him "from a Greek in England into a Greek Englishman". At school he discovered a taste for history and his facility for languages, adding German and Italian to the English and French that he spoke at home. He took a first in history at Balliol College, Oxford, in 1934, hoping to join the diplomatic service, but his father's French birth debarred him. He consulted Anthony Eden, only to be told that he would never get anywhere with his surname. Instead, in 1935 he became a barrister specialising in chancery law, and three years later married Barbara Eden, the daughter of Lord Henley.
The second world war transformed his life, although at a War Office interview, he saw a note on his file: "No good for anything – not even intelligence." However he was commissioned in RAF intelligence, and, in early 1941, found himself at Bletchley. He spent the rest of the war as deputy head (and from December 1944 head) of a small, secret section dealing with Luftwaffe Ultra intelligence, translating and interpreting decrypted Enigma signals. This enterprise remained a secret until the 1970s, after which Calvocoressi wrote its history in Top Secret Ultra (1980).
Outside the North African campaigns and in the battle against U-boats in the Atlantic, he felt that claims for Ultra's importance had been exaggerated, though admitting the psychological advantage of knowing the German order of battle: "It took the blindfold off our eyes, so that we could see the enemy in detail as he could not see us."
In 1943, appalled by their temporary lodgings, he and his wife (with their two young sons) bought a large house near Bletchley at a few hours' notice and lived there for the next 39 years. Music was a lifelong passion, and with the connivance of the Bletchley billeting officer he ensured his lodgers always had two violins, a viola and a cello to provide regular quartet concerts.
In the 1945 general election, Peter stood as a Liberal candidate, but lost in the Labour landslide. From 1950 onward, he unhesitatingly voted Labour in every general election. Later in 1945, now with the rank of wing commander, he was seconded by British intelligence to Nuremberg. He interviewed many German commanders and, during the trial, cross-examined Field Marshal Gerd von Rundstedt in court.
His wartime experience made him unwilling to return to his prewar life at the bar. For five years from 1949 he worked at Chatham House, writing five volumes in the series of Annual Surveys of International Affairs begun by Arnold Toynbee. In 1954 he became a partner in the publishing firms of Chatto & Windus and the Hogarth Press.
He continued to take public roles. In the 1950s and 60s, he was a member and later chairman of the Africa Bureau, founded by his friend David Astor, proprietor and editor of the Observer, as a political lobby concerned with apartheid in South Africa and decolonisation. From 1962 to 1971 he was a member of the United Nations sub-committee on the prevention of discrimination and protection of minorities. In the late 1960s he was asked to arbitrate on internal disputes at Amnesty International that threatened to destroy the organisation. He was always proud of his successful intervention, and that Amnesty survived.
In 1965 he left publishing to take up the post of reader in international relations at Sussex University that was created for him. In 1972 he was enticed back by the offer of the newly created post of editorial director of Penguin Books. He was later appointed publisher and chief executive, but in a series of disputes with the owners, Pearson Longman, he was obliged to resign in 1976.
In 1990 he received an honorary doctorate from the Open University for his direction of its publishing division in the 1980s (later sold for a handsome profit). He continued writing books, including the two volumes of the Penguin History of the Second World War and Who's Who in the Bible (despite being a lifelong atheist).
Barbara died in 2005 and the following year he married Rachel Scott. They lived in London and in Dorset, where he died. He is survived by his sons, Paul and David, and by three grandchildren.
John Tusa writes: Young radio producers at the then BBC External Services at Bush House in the 1960s regularly turned to Peter as a contributor. He was incredibly well informed, he was wise, he was dispassionate, he made himself available. Peter was part of our education, a kind of continuation of university seminars. This was an important part of his makeup, believing in the importance of passing on knowledge to the young. He loved keeping in touch with former pupils and producers.
When my wife, Ann, was writing her history The Nuremberg Trial, Peter was a wise and shrewd helper, not because of the part he played in it but because of his overall sense of its importance in the postwar world. We dined with him a few months back; it was as if no contact had been broken in 40 years. And we roamed not only over the cold war but over the dilemmas of the present time, on which his judgments were typically sharp.
• Peter John Ambrose Calvocoressi, writer and academic, born 17 November 1912; died 5 February 2010