^ Yeah, clearly he's well known because of all the Wimbledon titles. A lot of brits only watch Wimbledon, and a large chunk will only be interested in tennis enough to watch the final.
It's not just the winning though - Sampras won as many Wimbledon titles and didn't have that sort of following. Federer almost seems British so that might have something to do with it.
Underdogs who put up a good fight are also roundly appreciated not just the winners.
Sampras didn't have that kind of following because their heartthrob Tim Horton wasn't able to get past Sampras to win Wimbledon. Tim is and was clearly far more popular than Murray. Heck, Andy had to win Wimbledon to win some of their precious love. Before then, it was mostly hatred especially from the English. That comment regarding the English footie team that Andy had made was just a pathetic excuse to hate him even more. People are aware of the ongoing conflicts.