[2] Both parents were Jewish, his father a member of the Rothschild banking family and his mother the daughter of the first titled Jew in Austria.

[3] At Trinity College, Cambridge, Rothschild read physiology, French, and English, and was considered impressive enough an undergraduate to be spared the rigours of sitting the Natural Sciences Tripos, thus allowing him to embark immediately on a career in scientific research.

[2] He played first-class cricket for the University and Northamptonshire, where his experience of batting against the Nottinghamshire pair of Harold Larwood and Bill Voce he was later to describe as the most alarming of his life.

[13] With his assistant Theresa Clay, he ran the "Fifth Column" operation, which saw MI5 officer Eric Roberts masquerade as the Gestapo's man in London in order to identify hundreds of Nazi sympathizers.

(1999), an account of CIA propaganda during the Cold War, author Frances Stonor Saunders alleges that Rothschild channelled funds to Encounter, an intellectual magazine founded in 1953 to support the "non-Stalinist left" to advance US foreign policy goals.

Flora Solomon claims in her autobiography that in August 1962, during a reception at the Weizmann Institute, she told Rothschild that she thought that Tomás Harris and Kim Philby were Soviet spies.

In 1971 Rothschild was awarded an honorary degree from Tel Aviv University for ''the advancement of science, education and the economy of Israel''.

In this, he was unsuccessful as Jacob resigned from the bank to found J. Rothschild Assurance Group (a separate entity, now St. James's Place plc).

In 1982 he published An Enquiry into the Social Science Research Council at the behest of Sir Keith Joseph, a Conservative minister and mentor of Margaret Thatcher.

[citation needed] He appears several times in the book Spycatcher, which he hoped would clear the air over suspicions about his wartime role and the possibility he was involved in the Cambridge spy ring.

[citation needed] In early 1987 Tam Dalyell MP used parliamentary privilege to suggest Rothschild should be prosecuted for a chain of events he had "set in train, with Peter Wright and Harry Chapman Pincher" which had led to a "breach of confidence in relation to information on matters of state security given to authors".

[citation needed] In his 1994 book The Fifth Man, Australian author Roland Perry asserted that in 1993, after the dissolution of the Soviet Union, six retired KGB colonels, including Yuri Modin, the spy ring's handler, alleged Rothschild was the so-called "Fifth Man": "Rothschild was the key to most of the Cambridge ring's penetration of British intelligence.

"He was able to introduce Burgess, Blunt and others to important figures in Intelligence such as Stewart Menzies, Dick White and Robert Vansittart in the Foreign Office ... who controlled MI6.

Marmaduke Hussey, who was Chairman of the BBC Board of Governors at the time, implied Rothschild initiated the Milne sacking in his autobiography Chance Governs All.