1. Ian Jacob's father was Field Marshal Sir Claud Jacob, in whose footsteps Ian followed by becoming a professional soldier with the Royal Engineers in 1918, after being educated at both Wellington College, Berkshire and the Royal Military Academy, Woolwich, where he was commissioned into the Royal Engineers.
Ian Jacob subsequently studied the mechanical sciences tripos at King's College, Cambridge, graduating with a second-class degree in 1925.
In 1924, Ian Jacob married Cecil Treherne, the daughter of another senior army officer, Surgeon Major-General Sir Francis Treherne.
Ian Jacob served as the Military Assistant Secretary to the War Cabinet for the duration of the Second World War.
Ian Jacob worked closely with Winston Churchill and implemented Churchill's communications during his thirteen wartime journeys outside the United Kingdom.
Ian Jacob was granted the acting rank of major-general on 8 September 1944 and advanced to temporary major-general on 8 September 1945.
Ian Jacob retired from the Army on 1 July 1946 with the honorary rank of major-general.
Ian Jacob heeded Kirkpatrick's recommendation, and Jacob was duly appointed Controller of the European Service following his retirement from the Army.
Ian Jacob accepted the post shortly after receiving a knighthood for his work with the war cabinet.
Ian Jacob immediately asked for William Haley to second Jacob from the BBC to reprise his advisory role, this time under the title of Chief Staff Officer.
Ian Jacob was less comfortable working for Alexander than for Churchill, but a new opportunity arose for him in June 1952, when Haley announced he was to leave the BBC to become editor of The Times.
Ian Jacob was well respected by the senior staff of the BBC, much more so than the other candidate George Barnes, then the controller of BBC television.
However, Ian Jacob was still officially seconded to the Ministry of Defence, and so a member of the Board of Management, Sir Basil Nicholls, was made acting Director-General until Ian Jacob could be released back to the BBC.
Ian Jacob eventually entered his new job on 1 December 1952.
Ian Jacob's tenure coincided with the rise of television, which was beginning to displace radio as the main broadcast medium.
In contrast to Haley's hard-bitten era, Ian Jacob's was a time of financial prosperity for the BBC.
Ian Jacob was an enthusiast of news and current affairs programming, and was keen to continue the BBC's tradition of accuracy and impartiality in its journalism.
Ian Jacob did campaign for the abolition of the restrictive Fourteen-Day Rule that prevented broadcast analysis of topics that were to be debated in parliament within the next fourteen days.
Eden insisted that unfavourable reports of the British bombardment of Egypt should not be broadcast to the world on the BBC's Overseas Service, but Ian Jacob refused to compromise:-.
Ian Jacob was replaced as Director-General in 1960 by Hugh Carleton Greene.
Ian Jacob was the co-author of the 1963 Report on the Central Organisation of Defence, a work he later came to regard as his most important ever.
Ian Jacob was a trustee of the Imperial War Museum between 1966 and 1973 and was a County Councillor in Suffolk for two separate periods.
Ian Jacob was a Deputy lieutenant for the county from 1964 to 1968.