In 1933, Churchill noted that Germany had been overtaken by a racist government that was violating Versailles, and said that Britain should intervene. Churchill correctly noted, in the '40s, that, had Britain acted as he recommended in '33, World War II could have been averted without bloodshed.
Churchill further noted that, when Britain finally declared war in '39, the Nazis defeated Britain within 6 months. Churchill drew a straight line through the data, and said that, had Britain responded to German armament with a police action in '35, World War II could have been averted with only a small amount of bloodshed; he went on to speculate that, had Britain declared war on Germany in '38, the war would have been difficult, but would have been resolved in Britain's favour.
Waugh stated that, had Britain gone to war in '38, it would have been with the wrong allies for the wrong reasons. Waugh idolized the actual British policy, a rather unusual position, given the net results. Waugh agreed that Britain had to go to war in '39 for moral reasons, even though it was not in Britain's national interest.
In fact, after abandoning appeasement for war and declaring war on Germany, Britain was quickly defeated. That is, defeated as the US was in Vietnam, not (quite) defeated as Germany was in '45.
With perfect 20/20 hindsight, Britain and France should not have declared war on Germany in '39, since it was, morally valiant or not, a war neither could win.
Appeasement in '38 delayed the defeat of Britain and France for a year; appeasement in '39 might have delayed their defeat indefinitely, since Hitler said his only interest was in Eastern Europe, not in Western Europe, until Western Europe declared war on him. Of course, Hitler was not the most reliable of guarantors, but it does seem that, had Western Europe not declared war on Hitler, that he might have dissipated his forces against the USSR.
But, after The Gathering Storm, appeasement has been a useful blob of mud to throw at one's political opponents.