Churchill did not give a speech in 1946 calling for “a United States of Europe”."
"Great Britain, the British Commonwealth of Nations, mighty America, and I trust Soviet Russia - must be the friends and sponsors of the new Europe and must champion its right to live and shine."
A friend, sponsor or champion is not the same thing as a member.
Both sides of the argument have misappropriated Churchillian quotes to their respective causes.
The oft-quoted 1930 speech in which he said "We are with Europe, but not of it" was a statement of the then-current position - and was made 25 years, and a World War, earlier than many Brexiteers claim.
Even his 1963 quote that "The future of Europe if Britain were to be excluded is black indeed", is ambiguous about the outlook for the UK.
And of course he has had nothing to say on the subject for over fifty years - the world was a very different place in 1965.