Crashing, Channel 4

Created and written by the abundantly talented Phoebe Waller-Bridge, who also stars, Crashing is set among a group of twenty- and thirtysomethings living in a disused hospital in London, which the characters are “protecting” – sort of legalised squatting, where the sanctioned occupants pay a small rent and protect the building from being taken over by, well, squatters.

It was filmed in an actual disused hospital, with lots of rooms and shared spaces such as bathrooms, which lends bags of atmosphere and allows the story to have several strands.

In the first episode we saw Waller-Bridge's Lulu joining her old friend Anthony (Damien Molony, both pictured below), who is living at the hospital with his uptight fiancée Kate (Louise Ford) so they can save money to get married. Lulu likes people to think she's wacky (she carries a ukulele around and starts crooning at the drop of her metaphorically cocked hat) but actually is desperate to fit in – a quality efficiently parlayed by her ripping her tights on the way in to the hospital after she sees a cool-chick occupant dressed in that way.

Lulu and Anthony have history and play out a rather queasy flirtation with disturbing undertones; are they innocently play-acting, or are they involved in a more dangerous game of you-go-first? It's clear there's sexual tension, and the rather mousey Kate – who likes order in her life – feels unable to live up to it. She tries to undermine Lulu at every turn, but is thwarted by the fact that her nemesis is the kind of woman that everybody likes.

The other oddballs who make up the main cast are the irritating and priapic posh boy Sam (Jonathan Bailey) - "I'm an estate agent so I'm allowed to be a twat" – who forms an "is he, isn't he?" attachment with the shy Fred (Amit Shah), and the depressed and recently divorced Colin (Adrian Scarborough, doing a good job of looking out of place) to whom the much younger Melody (Julie Dray), an artist, takes a shine. So three couples (albeit one triangular)...

Crashing is a very 21st century sitcom, as anybody trying to buy a home in London could attest, but the sit and the com are rather conventional. It's no Fresh Meat, nor even a modern-day Friends, but Waller-Bridge has a good ear for a funny line (if not always for believable dialogue), and an acute eye for visual comedy, as evidenced by last night's wonderfully played mime scene between Lulu and Kate.

The improvement between the first and second episodes was marked; in the opener Waller-Bridge was trying too hard and so many of the jokes, characters and set-ups were all telegraphed. Last night, however, she provided more light and shade to her characters – Sam has just lost his dad and Melody has artistic as well as romantic designs on Colin – and the humour was more subtle. When it calms down and stops trying to be too cool for school, Crashing will be very much worth watching.