Golden Oldies (Thursday BBC1) was the latest documentary to be much too good for its 10.35pm, after-the-news slot. It was there perhaps because it didn't have an enormous hook: we met three old people who have ended up alone.

First there was the fried TV gold of Doris, 84, bent double but zipping round Clacton with a canvas trolley, past the funeral parlour ("Not today, I haven't time") to the discount warehouse for unbranded packet soup, then on to a drop-in centre for a hot lunch, some of which went in Tupperware for later. Doris had recently suffered a mugging, a fox living in her sitting room, and a long hospital stay during which someone cleared out her house without asking. This last mystery hung around and then drifted away unsolved, like a demented woman's memory that everyone else has to accept.

Doris, however, was miles from demented. None of her deprivations ("The dog died of shock. I'm on my own") had taken away her playful, pugnacious wisdom or resonant voice, every consonant edged with the flint of someone who learned to love their own eccentricities decades ago. A man on a bus had recently chided Doris for wearing odd shoes. "I said, 'Those legs and feet are both in trouble, and they're different sizes. They have different requirements.'"

Doris had a failsafe way to remain chipper. "If you are burdened, set it down, pen to paper, address it to someone you respect very much, or else the Lord himself - and then burn it."

Francis in Liverpool and Kitty in Exeter weren't so lucky. He was a recluse in a freezing hovel of a house, where the bath, kitchen sink and cooker had long since failed. Francis slept in an armchair in six layers of clothes – in front of the TV screen, because it was the nearest thing he had to the outside world. It wasn't emphasised, but you assumed being widowed was what he'd never recovered from.

Kitty pored over photos of herself 50 years ago when she was hot, painfully comparing them to the present. In the council flat she slid into occupying years ago after suddenly leaving her obsessive, controlling husband, Kitty's best friends were mugs, chairs and tables.

All three abhorred the idea of going into a care home, but the price of their unfailing intelligence and astonishing resilience was living out one of the scariest prospects of growing old: being aware of the person you used to be, while knowing that they've gone and can only be mourned.

The best thing Golden Oldies did was to let Francis, with what looked like it could be one of his last acts, give a warning to others. "Life is too short," he said, clutching an old Beatles 45. "It should be a rehearsal the first time. You should have a second go. Because I know I've made a complete mess of mine."

Girls (Mondays Sky Atlantic) finally arrived in the UK having gone through the same tidal hype it suffered in the States in April: rushing, sweeping praise that then ebbed as naysayers reacted to the big claims being made for it. That first high-water mark is the one to go by: Girls is extraordinarily good. It looks at other current comedies and says, oh yes. People did used to do it like that, didn't they?

The dazzling freshness of writer/creator/director/star Lena Dunham (at the end, her name insouciantly stayed still on the screen while various credits flashed past) is almost as hard to describe as it will be for the inevitable knock-offs to imitate. But the key scene was Dunham's alter ego, Hannah, having sex with her sort-of boyfriend on his couch: icky-funny, as she prattled and wobbled throughout and he tried to initiate desperately unsexy role-play, but somehow stirring by dint of its lacerating honesty.

Girls takes hateable, self-obsessed Brooklyn rich kids, with their apartments and their internships at publishing houses, and makes you love them because they're laid bare so disarmingly. Hannah became attractive as Dunham sprinkled her with naïve quirks and failings - all the more so because, while Dunham can write smart lines and neat set pieces when she wants, Girls steered away from every familiar cliché, unfurling casually to create the sort of funny that comes from what someone you know did, not a clever thing someone said. Dunham's characters are the roundest and rawest on TV. That they're almost all women is a bonus; that they're all white and privileged is irrelevant.

At least, it's not important in terms of assessing the merits of Girls, which deliberately sets itself in a stiflingly small world. In the show, wasting opportunities others would kill to have, and knowing that's what you're doing even as you do it, is what defines the characters and connects them to us. You could almost imagine an 84-year-old Hannah, all by herself.

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