Last Night's Viewing: Room at the Top, BBC4 Mrs Biggs, ITV1

The commonest vice of period drama is that of condescending to the past. It's all too easy to do it, given that we know lots of things they don't yet. We're inclined to conceive of ourselves as the adults to their children and then smirk affectionately at their innocence, forgetting that we usually only know what we know because they started to work it out for us.

One of the good things about Room at the Top, Amanda Coe's adaptation of John Braine's 1959 novel about a chippy young man on the make, is that it doesn't ever feel casually superior to the times it depicts. Another is that the script is full of lines that have an unexpected bounce: "You just slip new ones into the frame when you're sick of them," says Joe Lampton's landlady as she points out the fine art prints in his room, a line that does nothing for the advancement of the plot, but a lot to enrich our sense of this as a drama of social aspiration. "The coupons in that skirt!" a woman mutters enviously as the local beauty steps out of a sports car, and in just five words you're given a tangle of post-war history and class demarcation.

Lampton is back from the war with qualifications he didn't expect to get, and hoping to rise higher still. He's got a room at "t'Top", the smartest part of town, but he's only renting and he wants to own his status not just hire it. What he's got going for him is ambition and sex appeal that can silence a busy typing pool. He only has to enter a room and the insinuations start to fly. "Have you ever dabbled, Joe? With thespians?" murmurs Eva, a local vamp, as she encourages him to join the local am-dram group. This can get a little over-feverish at times, as if we're watching a 1950s version of a Lynx advert, but then, as Eva says, "they're short of men" and Joe's rivals aren't exactly polished. "Strictly frottage, old son," advises a workmate as Joe eyes up one of the secretaries. "She's got the strength of an all-in wrestler."

Joe, played by Matthew McNulty with a sulky confidence in his looks, can take his pick, but settles on two prospects – Susan, the moneyed daughter of an important local councillor and Alice Aisgill (Maxine Peake), a leading light in the am-dram society, who identifies Joe as a possible diversion from her loveless marriage. "I've low tastes, I warn you," she smoulders at him in the pub, as susceptible to double entendre as every other woman when in Joe's presence. This could easily have become over-heated too, but Coe inaugurates their affair in a scene that nicely combines melodrama and bathos. "Light it for me, like in the movies," Alice tells Joe as they sit having a smoke in her car. The cigarette action that follows is as urgently erotic as a Bette Davis weepie, but when Alice inhales she coughs and splutters, grounding the moment perfectly between celluloid dreams and Yorkshire reality. I've watched this twice now – the first broadcast having been pulled at the very last minute because of a copyright dispute – and it looks even better the second time round.

Mrs Biggs has been pretty nicely done too, though I can never entirely shake a doubt about whether it should have been done at all. Does this story of a middle-class girl tugged along in the wake of an underworld rogue really deserve five episodes in prime time? And might its portrait of Ronnie perhaps be a tiny bit starry-eyed and adoring? I don't suppose the Melbourne authorities were exactly models of humane empathy back in the Seventies, but stretches of Jeff Pope's script came very close to suggesting that they were infringing Ronnie's human rights by actually trying to catch him.

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