Did Churchill actually say the things attributed to him?
Frequently not. Churchill is one of the most over-attributed figures in history — a magnet to whom orphaned quotations drift, because a witty line sounds more plausible coming from him than from an unknown.
Why he attracts misattribution. He was genuinely prolific and genuinely quotable, wrote and spoke enormously, and won a Nobel Prize in Literature. That established a plausibility that unattributed remarks then attach themselves to — a well-documented pattern in which quotations migrate toward famous speakers, sometimes called Churchillian drift.
Commonly attributed and not his:
"If you're going through hell, keep going." No source in anything he wrote or said.
"If you're not a liberal at twenty you have no heart; if you're not a conservative at forty you have no brain." Versions predate him and he is unlikely to have said it, having changed party in the opposite direction at the relevant age.
The exchange about being drunk and ugly, which circulated as a joke before being attached to him.
"Success is not final, failure is not fatal." No record.
The remark about cutting arts funding during the war — "then what are we fighting for?" — which is not in any record and is inconsistent with what he actually did.
What he genuinely said is frequently better than the inventions: the wartime speeches are extensively documented, and so is a great deal of sharp, cutting and occasionally objectionable material.
Why it matters beyond pedantry:
Misattribution launders a claim's authority. A sentiment gains weight it did not earn, and the actual author disappears.
It simplifies the figure. A man who held genuinely contested and in some respects indefensible views becomes a dispenser of motivational aphorisms.
How to check a quotation: find the original source, not a quotation site; check whether the earliest attestation postdates the person's death, which is the strongest single signal; and consult a reputable quotation dictionary, which records attributions and their evidence rather than repeating them.
Other magnets include Twain, Einstein, Lincoln, Wilde, Gandhi and Orwell — and the pattern is identical.