He took the chairmanship of the Prime Minister’s advisory committee on business appointments of Crown servants, which was perhaps the first attempt to tackle what comes under the generic title of “sleaze”. It was an indication of his good sense and tact that he retained the personal confidence of Harold Wilson, Jim Callaghan and George Brown, however irritated the latter could become with him. I am told that on more than one occasion he declined a department of his own, such as the important Ministry of Power, because he felt that he could do more good for the party in the Treasury.In 1970 Diamond lost his Gloucester seat. Political opponents respected him, in particular the formidable Iain Macleod, who was to be Chancellor of the Exchequer in 1970 and who had frequently debated with him. I remember, too, being told by the bullion broker and expert on the gold market Sir Henry D’Avigdor Goldsmith that he regarded Diamond as one of the best financial ministers in any government he had known.

But on his return, with his added business experience, Diamond was an obvious choice for the Shadow Treasury team, where his knowledge and experience was of huge value in dealing with the Finance Bill. When Labour came into government in 1964 and I was a backbench and therefore pretty silent member of the committee stage of the Finance Bill, I marvelled at how very competent and convincing Diamond could be faced with the wrath of John Boyd-Carpenter and many other formidable Tories who had experience of both government and the City.It was not only Labour members who were impressed. For 15 years from 1950, he was Treasurer of the Fabian Society and as a young Fabian, when we attended Fabian summer schools at Dorking and elsewhere, I remember very well in the 1950s how a generation of us were impressed by Diamond’s command of an economic area in which we knew the Labour Party was weak.I do not like the term “retread” for those who have lost a seat in Parliament and returned for another constituency. Having held Blackley by a whisker in 1950, he succumbed to the Tory victory of 1951 and was unable to be selected for a seat (not that he tried all that hard), until an awkward by-election at Gloucester suggested that he would be an ideal candidate for a cathedral-city electorate.Diamond’s business life as a chartered accountant had been extremely successful and he was relied upon by Hugh Gaitskell after he became leader of the Labour Party in 1955 as a source of technical expertise and wise judgement.

He was mooted as a possible Deputy Speaker or indeed as the first Labour Speaker of the Commons.That was not to be. He was one of two chairmen of the committee stage of the Gas Bill, which was the longest and most contentious that parliament had known. To his surprise, he was selected because, so he explained, Catholics would not vote for a Protestant and Protestants would not vote for a Catholic, but both were happy to choose a Jew.Competition for ministerial posts in the Attlee government was fierce and Diamond, apart from a few months as Parliamentary Private Secretary to the Ministry of Works, saw his role as being a solid committee member and indeed a chairman of parliamentary committees, where his incisive mind made him acceptable to colleagues of all parties. His friend Bill Rodgers, now Lord Rodgers of Quarry Bank, said, Jack Diamond was on the Labour Party headquarters list of prospective candidates when he presented himself in Manchester to the Blackley Labour Party prior to the 1945 election. When he became Chancellor of the Exchequer in 1964, Callaghan plucked Diamond out from the back benches on account of the administrative and financial skills which he had brought to the service of the Labour Party. However, he was persuaded by his Fabian friends – among whom was Austin Albu, later to become MP for Edmonton, Middlesex, who had persuaded him to join the Labour Party – to go forward for the Manchester Blackley seat, which was thought to be unwinnable.In the Labour landslide of 1945, Diamond was swept in to Parliament but did not become a minister, unlike his contemporaries Hugh Gaitskell, Harold Wilson and a number of trade-union MPs including James Callaghan.