Calvocoressi was born in Karachi, now in Pakistan, to a family of Greek origins from the island of Chios. His mother, Irene (née Ralli), was descended from one of the founders of Ralli Brothers, who were prominent Greek families of Chios who came to London at the time of the Greek Diaspora. When he was three months old, the family moved to Liverpool, England.
Calvocoressi's father Pandia had spent the first seven years of his life in Manchester and the next ten at San Stefano (on the outskirts of Istanbul). He attended the Sorbonne from the age of 17 for three years and then joined the family firm in New York. Pandia Calvocoressi and Irene Ralli married in London in 1910. Shortly afterwards Pandia was posted to India where Calvocoressi was born. His mother and maternal grandmother were both born in India but spent most of their lives in England.
In 1926 he was elected a scholar of Eton in second place, a position which he retained for the greater part of the next five years. Switching from the standard Classical curriculum to History, he was taught by, among others, the young Robert Birley. At Balliol College, Oxford, in 1931–1934, he was tutored in Modern History mainly by B. H. Sumner and V. G. Galbraith, obtaining a First.
He was called to the Bar in 1935 and worked in Chancery Chambers until the outbreak of World War II. He spent most of the war as an RAF Intelligence officer at GC&CS Bletchley Park. He worked in 'Hut 3', where decrypted Enigma messages were translated and analysed, and Ultra intelligence was prepared for dispatch to commanders in the field. Calvocoressi rose to be head of the Air Section, which dealt with Luftwaffe intelligence. In summer 1945, he was accredited by British Intelligence to obtain evidence for all four Chief Prosecutors at the International Military Tribunal at Nuremberg. As a member of the British prosecution team, he cross-examined former German Field Marshal Gerd Von Rundstedt during the trial. Calvocoressi later advised the US Chief Prosecutor (General Telford Taylor), who had been his Bletchley colleague, in some of the American follow-up trials (1946–1949).
In 1950–1955 he worked at the Royal Institute for Foreign Affairs (Chatham House), writing five volumes in the series of Annual Surveys of International Affairs which previously been written by Toynbee. From 1955 to 1966, he was a partner in the publishing firms of Chatto and Windus and the Hogarth Press. From 1966 to 1973, he was Reader in International Relations at the University of Sussex, a post which was created for him.
In 1973 he was enticed back to publishing by the offer of the newly created post of Editor-in-Chief of Penguin Books. He and was appointed Publisher and Chief Executive of Penguin in the following year. But by 1976, he fell into disagreements with Penguin's parent company Pearson Longman, and was removed in 1976.
During this period (1955-1976) he was for 10 years a part-time member of the United Nations Sub-Commission on the Promotion and Protection of Human Rights, and was Chairman of the Africa Bureau, the London Library, Chios Charities, and Open University Enterprises Ltd. He also served on the governing bodies of Chatham House, the Institute of Strategic Studies, and Amnesty International.
He wrote 20 books, mostly on contemporary history; one of these – World Politics Since 1945 – passed through nine editions. Threading My Way, an autobiography, appeared in 1994. He set private life before and above his career and never had cause to question this priority.
In 1990, he was awarded an honorary doctorate by the Open University.
- Who's Who in the Bible
- Total War: The Story of World War II
- World Politics Since 1945
- The Penguin History of the Second World War
- Top Secret Ultra
- A Time for Peace
- The British Experience 1945-75
- World Politics, 1945 - 2000
- Suez Ten Years After
- Independent Africa and the World
- Freedom to Publish
- Resilient Europe: A Study of the Years, 1870-2000
- Nuremberg: The Facts, the Law and the Consequences
- Fall Out: World War II and the Shaping of Postwar Europe
- Threading My Way
- Survey of International Affairs, 1947-1948
- Survey of International Affairs, 1949-1950
- Survey of International Affairs, 1952
- Survey of International Affairs, 1951
- Survey of International Affairs, 1953
- Interview with Peter Calvocoressi by Roger Adelson