This 'alternative to Churchil' question got this reply on another bard a while back.
Churchill was not a working-class hero and not a particularly attractive personality but he had the charisma to do the job. However, the fact that he was given the boot even before the war was over shows that he was not seen as anything else but as a war leader.
I can't see any other Conservative who could have done the job. Churchill's sidekick, Eden, didn't have the determination. On the Labour side, Attlee, who steered the country through the final phase of the war, certainly had a steely determination but not the charisma. Who else on that side? Bevan, the fiery Welshman, was too volatile. If I had to choose one, I would say Ernie Bevan, a formidable leader who rose from nothing to become Foreign Secretary, the same sort of spectacular rise as Robertson's in the military in the First World War.
But, who can tell who would have risen to the occasion if they had the job? The most unlikely people achieve remarkable results.
There really were none, for Churchill was seen as the only true "Warrior" among parliamentarians of the day. WSC stated on many occasions that he was a "War-person," meaning that he thrived intellectually on conflict and battle. His record would surely indicate this.
It is interesting to note that the aged Lloyd George always fully expected to be brought into the Cabinet in some capacity or form, but of course he was too aged, too untrustworthy, and too mercurial to allow into the inner circle. One suspects that LG would have tried to cabal against WSC, as he did against Asquith in the Great War - and at any rate he would not have been given the opportunity, even if he had been young enough, which he was not.
The only possible Tory with requisite fight in him might have been Amery, but he did not hold enough gravitas among the House to even been a consideration. Halifax would have been all wrong. The rest, of them, including Labour, were all too scarred by the Great War to be as effective as WSC. Churchill for all his faults, retained the capacity to understand, in a quite Victorian way, that War was part of man's existence, and as such - was able to compartmentalise, and objectify his sentimental and emotional nature from the business-at-hand.