Baggs I think Johnson is popular because he's a "bloke". People can relate to him. They feel at ease. For all his faults, he's the kind of bloke you can talk to. He's a "common or garden", as the saying goes, man
I agree, but what I find interesting is that David Cameron (Eton-educated, posh voice, wife with impeccable taste) is perceived as elitist and out of touch, whereas Boris Johnson (Eton-educated, posh voice, fiancée with questionable taste) manages to convince swathes of the British people that he’s an ordinary bloke, just like them.
Perhaps those bloke-ish, foot-in-mouth comments paid off and were even part of a deliberately constructed persona. A high-risk strategy, but if it was, it seems to have paid off.