The Churchill Charmley paints is a fool whose racism and ambitions of empire were akin to Hitler's. Charmley even suggests that his greatest achievement, the resistance to Nazism, was fuelled by a dislike of Germans rather than any understanding of fascism.
Perhaps the professor would care to read page 96 of The Gathering Storm, where Churchill refers to the Night of the Long Knives as the actions of "a dictatorship based upon terror and reeking with blood" and says that he had been "deeply affected by the episode". Again, in a speech of 16 October 1938 he said, "A state of society where men cannot speak their minds, where children denounce their parents to the police, [such] a state of society cannot long endure if it is brought in continual contact with the healthy outside world".
Churchill knew exactly what fascism was. He understood it more than any of his contemporaries.