Which is better, British TV drama or American? A couple of years ago, merely asking the question would have had the hipsters chortling into their obscure US box sets — and even now a strange cultural cringe seems to persist. Nonetheless, I’d suggest, British television drama these days really is in the midst of an era that will have commentators in 20 years’ time routinely (if a bit unimaginatively) reaching for the adjective ‘golden’.