Well Churchill had his stroke in 1953...that wouldn't be hushed up in TTL. Either he would go then, or perhaps retire beforehand after losing the election. Eden takes over and most probably wins in '56. Has the potential to change quite a lot: even more nationalisation, for one thing, and probably different decolonisation/Empire policies.
I wonder if Attlee would stand down during this term or fight the '56 election. Probably the latter, as even if he was ageing he knew that the Labour Party's right and left wings would have their usual punch-up as soon as he retired. I wonder how Attlee would have gotten on with Eisenhower.