The Telegraph, 05 Feb 2010
As head of air intelligence at Station X — the top secret headquarters at Bletchley Park of the codebreakers who cracked Germany’s Enigma cipher during the Second World War — Calvocoressi played a critical role in the operation to intercept high-level German orders. This intelligence, known as Ultra, and provided by his team of mathematicians, linguists and other experts, not only helped win the Battle of Britain but also furnished details of Hitler’s proposed invasion in Operation Sea Lion, eventually abandoned as too risky.
Once the official secrets ban on the wartime operations at Bletchley Park had been lifted, Calvocoressi was at pains to repudiate the myth that Ultra had yielded advance information of the blitz on Coventry — “a good story that doesn’t lie down,” as he put it.
On the other hand he was always critical of the Allied bombing of Dresden, saying that Ultra had warned Allied air chiefs that, contrary to expectations, the SS Panzer army would not be returning through the city after the battle of the Ardennes. “The bombing of Dresden was terrible,” Calvocoressi declared long after the war, “and should never have taken place.”
His account of his wartime work at Bletchley Park, Top Secret Ultra, appeared in 1980. In it Calvocoressi emphasised the decisive role played by Ultra in intercepting communications: “Ultra took the blindfold off our eyes so that we could see the enemy in detail in a way in which he could not see us.”
The breaking of the Enigma machine ciphers gave Britain’s outnumbered fighter pilots a critical head start in intercepting German bombing raids. It also helped to end the Nazi wolfpack menace during the Battle of the Atlantic when, in December 1942, Bletchley Park experts cracked the U-boat cipher known as Triton.
In his book Calvocoressi also highlighted the contribution of the intercepts to countering the surface raiders which had inflicted such damage on Atlantic shipping. The best-known was the German battleship Bismarck, which had sailed from the Baltic in May 1941 on what would be her first and last voyage. Six days out from Gdynia she sank the veteran British cruiser Hood, but three days later she herself was sunk with the loss of some 2,000 hands, just short of the safety zone for which she was making off the western coast of France.
Calvocoressi described how Bletchley Park had played a part in locating Bismarck by revealing Luftwaffe preparations to provide the battleship with air cover as she approached Brest. Later the codebreaking station’s naval section intercepted two German signals transmitted before and after the sinking. The first, from Hitler himself, thanked Admiral Lütjens, Bismarck’s commander-in-chief, and assured his crew, as she headed for the Atlantic: “All Germany is with you.” The second, sent the following day, was a grisly inquiry from German naval authorities, asking: “Are bodies to be fished up?”
Peter John Ambrose Calvocoressi was born on November 17 1912 in Karachi, then part of British India, now Pakistan, into one of the great Greek mercantile families which could trace its roots back to Byzantium and which had flourished in a much intermarried enclave in late 19th-century London. Of these families, the most prosperous and successful were the Rallis, of whose bank his father was a director.
Moving to England at the age of three months, Peter was brought up at Holme Hey, a substantial house on the fringe of Sefton Park, Liverpool, and was dismayed to be called a “greasy Greek” at prep school in Kent. Largely on the strength of his Latin translation of Abide With Me, he won a scholarship to Eton (where he discarded God and identified himself as a political radical) and in 1934 took a first in History at Balliol. His parents wanted him to try for the Foreign Office but he was warned off by Anthony Eden, who said that with a name like Calvocoressi he would never get anywhere in the service — even if he succeeded in entering it.
In 1935 Calvocoressi made a start at the Bar, being called by Inner Temple, and when war came he was a newly-wed working as a temporary civil servant at the Ministry of Economic Warfare. On volunteering for the Army — “when Hitler turned west, sitting in an office in Berkeley Square no longer seemed good enough” — he was called in for tests and read, upside down, a form on a table that declared: “No good, not even for intelligence.” He discovered later that he had been rejected on the grounds that some years before he had cracked his head in a car accident in which his mother was killed.
Returning crestfallen to his desk, Calvocoressi was met by a secretary who suggested that he should write to her father — in his capacity as director of intelligence at the Air Ministry. Calvocoressi’s letter received an immediate reply, and his knowledge of French and German, honed during school holidays in Austria, commended him as a natural candidate for an intelligence role with the RAF.
Like many who were engaged in the vital and demanding work at Bletchley Park, and like many of Churchill’s own immediate entourage, he may have found that all subsequent work was in some ways a comedown. Well-off and loving music, he was able to buy a substantial house nearby and select lodgers from those among his colleagues who could entertain him with string quartets.
After the war, Calvocoressi’s knowledge of German operations qualified him for a role collecting evidence at the Nuremberg trials. Accredited to all four chief prosecutors, he provided facts about the activities of the German armed forces and the SS before and during the war. His knowledge of the vast quantities of captured Nazi documents meant that he knew where to look for relevant information as the various trials progressed.
Each day Calvocoressi watched “the once high and mighty ... led by Hermann Goering” troop into court. Goering, he said, “never disavowed Hitler or his crimes and had come to terms with the certainty that when the trial ended he would die”.
Later Calvocoressi assumed an undercover role, when secret service chiefs ordered him to discover what the Germans had known or suspected about the security of their high-grade wartime ciphers. Calvocoressi talked to General Martini, who had been head of the Luftwaffe’s interior intelligence unit, noting that “after a year in prison not talking to people, he was delighted to talk shop”.
Calvocoressi’s conclusion was that the Germans had had no idea that the Allies were cracking their ciphers so quickly.
After standing unsuccessfully as a Liberal candidate in the 1945 general election, Calvocoressi spent five years between 1949 and 1954 with the Royal Institute of International Affairs at Chatham House under Arnold Toynbee. He was later offered the post of director-general, but by then he had joined the board of the publishers, Chatto & Windus, which he was unwilling to leave, and where he spent the next 11 years.
His last official posts were as reader in international studies at the University of Sussex, from 1965 to 1971; chairman of the London Library from 1970 to 1973; a brief spell as chief executive at Penguin Books; and finally as chairman of Open University Educational Enterprises.
He wrote a number of books on history and international affairs, including The British Experience 1945-75 (1978), Independent Africa and the World (1985) and Who’s Who in the Bible (1987). He published his brief autobiography, Threading My Way, in 1994.
The range of jobs that he undertook was wide, and his habit of leaving them was partly due to the breadth of his interests and partly perhaps to a conviction that he knew best: although in theory he respected independent and individual attitudes, he also felt an obligation to guide others along the paths he selected for them. This cannot always have made him an easy colleague.
Peter Calvocoressi married, in 1938, Barbara Eden, a daughter of Lord Henley. She died in 2005 and the following year he married Rachel Scott. With his first wife he had two sons.