But I do want to point out that, if you've ever read Hunter S. Thompson's Fear & Loathing: On The Campaign Trail ’72, this isn't anything remotely new.
This is one of the oldest and most effective tricks in politics. Every hack in the business has used it in times of trouble, and it has even been elevated to the level of political mythology in a story about one of Lyndon Johnson’s early campaigns in Texas. The race was close and Johnson was getting worried. Finally he told his campaign manager to start a massive rumor campaign about his opponent’s life-long habit of enjoying carnal knowledge of his own barnyard sows.
“Christ, we can’t get a way calling him a pig-fucker,” the campaign manager protested. “Nobody’s going to believe a thing like that.”
“I know,” Johnson replied. “But let’s make the sonofabitch deny it.”
The tl;dr version for the benefit of David Cameron et al: Buy the ticket, take the ride...