Brits are fundamentally one of the most reserved and self conscious people on earth, and they need to drink to loose their inhibitions.
Weird, getting drunk, running about with cocks on their heads and having public sex is reserved, eh? I'd say other nations are far more reserved and prudish. America finds the display of female breasts offensive for instance, and drinking is looked on as some sort of sin.
Edit: you live in the most puritanical, stuck up, humourless countries in Europe and think the British are reserved.