It's helpful to have the 20/20 hindsight, of course! and there's times when a little roaring might do some good?!
Ha!
As he said himself the British people were the lions he merely gave them the roar and fundamentally, and not in any way wishing to denigrate him, Churchill’s greatness stems from his rallying an unsure and still semi-appeasing British people in the dark days of 1940, holding the fort as it were until Russia and the US got involved.
He rallied the British people with a couple of simply magnificent and sublime speeches that to this day can make the hairs stand on the back of your neck as you think about the context in which they were made and the effect they had on the world.
However, to be perfectly honest once the threat of invasion had passed any of half a dozen resolute men in the British cabinet could have taken over as wartime prime minister and done equally as well, indeed perhaps even better.