Harriet Walker on Television: Getting On, BBC4

Getting On gives me the spine-shivering feeling that I might be viewing terrifying reality

Anyone who has been in hospital will recognize the woozy rollercoaster of emotions that comes with it: one minute you're crying because you're worried you might wet yourself and no one will notice for three days; the next, you're crying because of the simple beauty of the human condition and our ability to cope with almost anything, even lumpy mash and grey cabbage. In hospitals, you may see the very worst of life, but there's a chance you'll catch the briefest glimpse of the best of it, too.

So – during my stay – with the nurse who insisted on calling her patients “losers” and counting every second until she could leave and go to the pub (she's joined the army now – I wish her all the worst with that career choice) came also the mild-mannered Polish cleaner who took the time out to pat my wild hair and tell me how strong I was, as I lay wimpering in a pool of my own urine.

It strikes me that hospital humour and bedside manners are two very British things – mainly because they shouldn't really be funny, and everywhere else medical care is too expensive to poke fun at. In any other country, the bleak business of being laid up is no laughing matter. In Britain though – perhaps because we invented the NHS and chloroform – we snigger at the sick and needle the needy like children picking up a dead pigeon with a stick and waving in their teacher's face. We're not scared of death or illness! Give us the bad news, Doc, we can take it!

Except we can't really. That's the central message behind the BBC4 series Getting On, starring Jo Brand and The Thick of It's Joanna Scanlon. A series in which there is so much mundane but metaphysical malaise it's a wonder anyone can stand up straight. A series so obsessed with minutiae that Brand's character, Kim, a care assistant, is constantly battling with locked doors that refuse to open and high-tech machines markedly less efficient than her own two hands.

Ward K2 is a purgatory of sorts – a place where patients are either full-blown hypochrondriacs (like the unfortunately named Mrs Deathick) or seemingly fine, like Enid who eventually proves perfectly capable of eating her own yoghurt despite having been spoon-fed for much of the episode. Meanwhile, a “stage 13” – that is to say, dead to the world to all intents and purposes – patient's private room becomes a useful office while the door to the real thing remains stubbornly locked.

Getting On gives one the spine-shivering feeling that you might be viewing terrifying reality, as if you too were lying prone in a bed more mechanised and more unruly than a bucking bronco as it all unfolded around your supine presence.

Part of this lies in the sheer genius and faux geniality of the dramatis personae – master-sketches from the awkwardly real school of characterisation, executed perfectly by director Peter Capaldi and a cast that brings together some of the finest deadpanners of the British sitcom circuit.

From the flunky who arrives with a basket of ethnic cupcakes to celebrate diversity (“the black, I mean, brown ones are particularly good,” splutters Scanlan's Sister Den Flixter through a mouthful of her third) to the consultant obsessed with a research programme focusing on vulvas of the post-65-year-old woman, everything is perfectly observed and accurately – if depressingly – strutted. No one uses the verb “do” if “task” will work better; no one has been on the right training scheme; everyone is knackered.

The hero of it all, of course, is Brand, whose put-upon assistant seems to be the lynchpin holding it all together, despite wanting to leave early and having run out of ketchup for her teenage sons. Every slightly dreary fag we see her light round the back of the building further cements her necessity, like a slightly bedraggled guardian angel for all the other crocks in the building.

The fact that she is the only character to exert some slight revenge, handing over her egregious consultant's Egyptian-cotton sheets to the neighbouring ward when they run out of linen, is testament to her role as a cheeky Ariel-esque sprite.

There are flashes, too, of Brand's signature comic hallmarks – the protracted reasoning which turns and tumbles over something utterly banal; brilliantly observed litotes; and heartbreaking human kindness – which mark Getting On as a sort of leitmotif for her career: from alternative, irreverent feminazi to national treasure.

So, by the time in the final scene when she throws her cagoule over the whizzy but broken piece of new technology – now boasting a sticker, as Brand's own professional tabard does, which reads “I need mending” – the action is so loaded with meaning and with humanity that the whole bleak affair seems infused with a rose tint.

That's what happens in hospitals: you have to make the best of things, and Getting On does just that.

Grace Dent is away

Harriet's Marmalade dropper

Nigella's frisson of disgust at the word “garnish”, so vulgar that she practically has to cross herself after she says it, making up for the slip by using “anoint” as a synonym for “rub”.