Not since Zola Budd have I heard anyone declare themselves to be British. But essentially, the subtext appears to be to discourage young Muslim boys from trotting off to Pakistan and coming back with explosives in their shoes. I'd have thought it would be simpler just to leave George Bush to fight his war on Islam"terror" by himself, and not alienate them in the first place - but then, I'm not a politician.
Artificially constructed political identities have been attempted before - Manuel Castells was famously involved in a project aimed at constructing a supra-national European identity. Not since apartheid times have I heard anyone defining themselves as European, either.
Of course, the other subversive identity that all this "Britishness" is trying to suppress finds its expression this evening - with the addressing of the haggis, on Robbie Burns Night. Anything to silence those bagpipes, I suppose...