Considering it's such a bleakly intimate comedy, Getting On attracts glittery attention. It's a favourite of Mad Men's Jon Hamm and, in the final episode, Oscar-winner Tilda Swinton has a wordless cameo as the assistant to a preposterously pretentious artist.

Swinton, barely recognisable with black hair, turns up on K2 ward with a bunch of kids doing an art project. Their teacher is a ludicrous bearded German who announces to his little group, "All human interraction is social sculpture." He then insists they pester the old ladies, adding, "Bodily fluids can also be part of the creative process", when one worries about her wee.

It's a lovely valedictory episode - hugely funny in parts, but brushed with sadness in others.

Honest, warm and human, Getting On's wry dramatisation of the inefficiences of the NHS is as clever as it is funny; the script is a credit to Jo Brand, Joanna Scanlan and Vicki Pepperdine. In the series finale, a group of schoolchildren arrives at the geriatric ward to sketch images of the patients and Sister Den (Scanlan) is sceptical: "Most are doolally, deaf or asleep. Good luck to them." Watch for cameo appearances by Hugh Bonneville and Tilda Swinton.

Tilda Swinton and her real-life partner Sandro Kopp cameo tonight; he plays art teacher Dylan Shwarz while she's his mute assistant Elke. "All human interaction is social sculpture," Shwarz tells his band of schoolkids, who must make artworks based on tales the patients tell them. "Well, they're all doolally, deaf or asleep, so good luck to you," retorts Den - who's in for a surprise later. Last in the sublime series, and therefore the last time Richard Hawley croons that lovely song over the credits - at least for now.