As Paul Addison puts it in his admirable short biography Churchill: the Unexpected Hero, Winston Churchill won two great victories in 1945, one in war and another in the battle for his reputation, which had been fought since the beginning of the century. His career had been long enough even before his apotheosis, and yet it had been in many ways very unsatisfactory, up and down, in and out, triumph and disaster.
Then came May 1940, the finest hour for him and the British people. When Hitler shot himself in the bunker five years later, Churchill was a world-historical figure, the saviour of freedom and civilisation. He was also 70, and that seemed the obvious time for him to retire from public life garlanded with every honour, the more so when Labour won its landslide victory in July 1945 and Churchill left Downing Street. Or it seemed obvious to many people, but not to Churchill. Far from stepping down, he remained at the forefront of national and international politics for another ten years.
He fought three general elections as Conservative leader, spending more than six years as leader of the opposition and three and a half as prime minister, before finally leaving Downing Street at the age of 80. This story - his life in the ten years after the war: his second spring, or second coming, though latterly near to second childhood - is the subject of Churchill Defiant by Barbara Leaming, an American writer who has previously published a book claiming (more interestingly than plausibly, in my view) that John F Kennedy's career was profoundly shaped by the influence of Churchill.
Even if one knows the narrative, it is still startling, and the questions are still perplexing: how did Churchill get away with it, and why did he want to? In the course of that amazing career, he had shown no great party loyalty.
In 1930 he could say rightly that the Tories had never liked or trusted him, and it is easily forgotten that, like David Lloyd George before him, when he became prime minister he led no party. During that finest hour in the summer of 1940, his coalition government included the leaders of the parties: Clement Attlee for Labour, Archibald Sinclair for the Liberals, and Neville Chamberlain, who resigned as premier on 10 May but remained Conservative leader until the autumn, when he was nearing death.
Although the Tories accepted Churchill in his place, without much choice at that juncture, many of them were still suspicious of him. Then the manner in which he fought - and lost - the 1945 election, egged on by the appalling Lord Beaverbrook to attack Labour as a totalitarian party, diminished his stature and increased the feeling that he should depart. That was what his formidable wife, Clementine, wanted, and not only she.
As Leaming relates, the election was barely over and Churchill leader of the opposition when "Conservative heavyweights met to find a way to manoeuvre him out of office". The man with the strongest motive was Anthony Eden. He had been foreign secretary before the war, resigning in 1938 in protest at appeasement (of Mussolini), and returned to the Foreign Office from 1940 to 1945 under Churchill, as whose heir-apparent he was now recognised.
In his late forties when the war ended, Eden was itching to take up the reins. But Churchill would not budge. His motives are understandable, if not all necessarily commendable. People who have run anything, from a government to a newspaper to a faculty, notoriously come to think that they are irreplaceable. Then again, Churchill had a point to prove: he had never led a party until he was 65, never led a party in an election until he was 70, and then he lost.
Once more he was determined to prove his critics wrong by fighting and winning an election, although in the event he barely achieved that. Many things went wrong for Attlee, with all his great achievements, but he still won the next election in February 1950, albeit with a small majority. Quite why he called another, unnecessary election in October 1951 is another question, though a fascinating one, yet while the Tories gained a parliamentary majority, Labour won a clear lead in the popular vote.
But Churchill's other motive was his belief that he had a final destiny that would be his legacy: he had won a war, and now he would win a peace. It would be easy "to retire gracefully", he told colleagues, but the international situation was too grave. He believed that he had come to understand Stalin at their wartime meetings, and that he alone could forge a lasting peace if he met the Russian leader again for "a parley at the summit" (the last being a word that Churchill bequeathed us).
Even if the belief was wrong, it was not ignoble, and it persisted after Churchill entered his second prime ministership. Less than 18 months later Stalin died, but that only stimulated Churchill's obstinacy: he was just as sure he could make terms with Stalin's successors. His comrade-in-arms Dwight Eisenhower was now in the White House, however, and in no way shared this view - yet another occasion when the "special relationship" was special in that only one side recognised its existence.
As a further complication, Churchill had a severe stroke in June 1963. It now seems unbelievable that all knowledge of this was kept from the public by a deliberate conspiracy of silence among the press lords, though months later the Daily Mirror hinted at the truth with the cruel headline "The giant in decay". That might have been Eden's moment - if he hadn't been in an almost worse medical state, aggravated by a botched operation that put him out of action for months.
This is an absorbing and detailed account, but it is a pity that Leaming is so reticent, seeing herself as a chronicler and offering little by way of her own interpretation. Yet when she does offer judgements, they may be dubious. She makes a great deal of the part played by Viscount Cranborne, or Lord Salisbury, as he became in 1947, who was one of the most active, if unsuccessful, conspirators trying to remove Churchill. It is true that he was then an important figure in the Tory party, but to claim that Eden benefited from "Cranborne's superior intellect" is absurd. Whatever else is said of him, Eden was a cultivated and clever man, with an Oxford First in oriental languages.
A senior cabinet colleague impatiently waiting to inherit from a prime minister who has promised to leave but keeps prevaricating . . . now what or whom does that remind us of? Eden never went so far as to call Churchill "a liar, a cheat and a fraud", as Gordon Brown called Tony Blair, though some of the exchanges in the earlier case were pretty ill-tempered, and the wait was too long.
In April 1955, Churchill finally did depart in a cloud of sentimental glory, but Eden was embittered by the lost years, just as Brown later was. Sad to say, both men soon came a cropper, as their predecessors had suspected might happen. On the evening before he presided over his last cabinet, Churchill said to an intimate, “I don't believe Anthony can do it." Change the name to "Gordon", and isn't that just what our penultimate prime minister felt?
Churchill Defiant: Fighting On (1945-55)
Harper Press, 400pp, £20
Geoffrey Wheatcroft is the author of “The Strange Death of Tory England" (Penguin, £8.99)