Well it was a general election with two main antagonists. Admittedly, the old saw that elections are lost rather than won has more than a grain of truth, as you're suggesting in this case. But the result was unexpected (and she did lose her overall majority: trashed?), it set alarm bells ringing on the right (as well as among the right in the Labour Party) and it triggered an onslaught by the right-wing media and from within his own party for the next two years. He is a naive, unspun man (not good qualities in a leader, I'm the first to admit) and he didn't know how to counter the attacks, and he accorded his opponents a field day when it came to brexit. Elections are won and lost for many complex reasons and it's impossible to to assign relative importance accurately to any one of them, but I take your point.

Cheers for your civilly-expressed and thoughtful disagreement, Nigel. We could use more of that.