In any list of the-best-prime-ministers-we never-had, the name of Roy Jenkins is likely to be prominent. He was intelligent, moderate, courteous, thoughtful: he was exactly the sort of man whom any civil servant would wish to see installed in No.10. That, no doubt, is why he never got there.

John Campbell makes no bones about the fact that he is a fan of Jenkins. He was, writes Campbell, ‘the first public figure I was aware of and always the one I most admired’. Campbell is far too sensible a man and good a biographer, however, to allow his book to degenerate into a paean of praise. Jenkins’s frailties are unsparingly exposed, his occasional failures recorded, his more extravagant pretensions ridiculed. The fact that, at the end of this long and thoughtful book, one ends up admiring and liking Jenkins more rather than less is a tribute to Campbell’s skills as a biographer but even more to Jenkins’s own personality and achievements.

He had his weaknesses. The most obvious was self-indulgence. He was self-indulgent when it came to food and drink, attaching great importance to consuming the right things in the right places. Many of his most important conversations took place over the luncheon or dinner table — Campbell could have saved several pages by omitting the words ‘at Brooks’s’ after the word ‘lunched’. He was self-indulgent when it came to women. He tended to have affairs with the wives of his closest friends: a trait which might sound unattractive but in fact caused little or no offence. Neither Ian Gilmour nor Mark Bonham-Carter seem to have resented the fact that their extremely attractive and intelligent wives had a fling with Jenkins, and if they did not mind why should anyone else? (Another fling was with Tony Crosland when they were undergraduates together. Judging by the correspondence, this relationship certainly had its physical side, but that element did not survive their years at Balliol and, anyway, always meant more to Crosland than it did to Jenkins.)

He was also excessively preoccupied by his social standing. He felt no shame because — indeed, took pride in the fact that — his father had started his working life at the coal-face, but he openly rejoiced at the gap between those origins and the conspicuous grandeur which he himself achieved. In his index Campbell lists ‘alleged snobbery’ among Jenkins’s characteristics. His use of the word ‘alleged’ is charitable, to say the least. Jenkins’s snobbishness is all too easily established. Campbell, however, fairly makes the point that this was more than the mere worship of class for class’s sake:

He liked the company of clever people of any class, but he especially enjoyed the social ease and sophistication that the well-born and well-connected tended to possess. In addition, he enjoyed their society because it connected him to the late-Victorian/Edwardian political world he wrote about in his books.

One of the things that drew him most strongly to Mark Bonham-Carter was that he was H.H.Asquith’s grandson: ‘Though not strictly aristocrats, Asquith’s descendants were political royalty, and by mixing with them he could feel close to his political model.’ Though he tried from time to time to reassert his proletarian roots, the effort became less and less convincing. When he was competing with Callaghan for the Labour leadership, one of his followers tried to canvas the support of a group of miners’ MPs in the House of Commons tea room. ‘Nay, lad, we’re all Labour here,’ was the kindly brush-off.

Jenkins’s finest hour came when he was appointed Home Secretary for the first time in 1965. Campbell writes:

Coinciding with the height of Beatle-mania, the miniskirt, the contraceptive pill and ‘Swinging London’, but also with the Rolling Stones, the drug scene and the first Vietnam War demonstrations, the period 1965-7 now appears, for good or ill, a turning point in the social history of the country — a halcyon time of personal liberation or the onset of national decadence.

For Jenkins it was emphatically the former. Given a remarkably free hand by Harold Wilson, spared the nagging conviction that was to haunt him in all his future roles — that it was he, not X or Y, who should be occupying No.10 — he steered through a wide range of liberal measures relating to flogging, homosexuality, abortion, theatrical censorship and above all race relations. In three years he showed not only that he was a man of principle with an almost visionary view of his public role but that he was a shrewd politician, patient, dexterous and uncommonly effective when it came to getting his own way.  In the eyes of most people it was a question not of if but of when Jenkins would become prime minister.

It was Europe that destroyed these hopes. With de Gaulle’s resignation in 1961, Britain’s way into Europe was dramatically opened. But terms which the Labour government had found perfectly acceptable when their party was in power suddenly seemed far less attractive when put forward by the Tories. ‘Because I want to see the Tories beaten, and because I am willing to use any weapon to beat them with, I am against EEC entry on these terms at this time,’ declared a youthful and horrifically honest Neil Kinnock.

Jenkins believed passionately that Britain’s proper place was in Europe and that to sacrifice the opportunity for achieving this for party advantage was not merely politically inexpedient but morally indefensible. With 68 other Labour MPs he defied the Whips and voted with the Tory government. ‘This was the proudest moment of Jenkins’s career,’ writes Campbell. It was also the most disastrous. With it ended any possibility that he would ever lead the Labour party; he was inexorably set on the path that was to take him first to the Presidency of the European Commission in Brussels and then to the brief flourishing and prolonged wilting of the ill-fated SDP.

Reviewing D.R. Thorpe’s biography of Selwyn Lloyd, Jenkins concluded that it was ‘a model biography of a middle-rank politician’. ‘I would consider myself very lucky,’ he went on, ‘if I were eventually done by someone as balanced, sympathetic and well-informed as Mr Thorpe.’ He would not have wished to be taken too much au pied de la lettre in his reference to a ‘middle-rank politician’ but John Campbell has more than fulfilled his criteria for his model biographer.