'Oooh! Your sex is on fire!' bellows the brilliantly hideous Clive as he returns from his wedding to Tanya, just before the occasion - like all others - quickly ping pongs out of control. Tonight, Simon has more antagonists than usual: aside from his family quizzing him over his career, there's his actor/director boyfriend
Ben - vague, mumbling and without Simon's best interests at heart. By the end of this finale we'll have had laughter, tears and an armlock - too good to end it all now, surely?

Have you been watching ... Grandma's House?

As Simon Amstell's sometimes uncomfortable sitcom nears the end of its second series, the performances and writing look increasingly impressive.

The second series of this sharp sitcom - in which Simon Amstell plays an insecure version of himself - ends tonight with an episode involving Pinteresque levels of family squabbling and unfulfilled ambition. The problems begin when Simon learns that his latest theatrical venture - a role in a production of Shakespeare's The Tempest - is in jeopardy, and they're compounded by some wonderfully bitter infighting between Tanya (Rebecca Front) and Liz (Samantha Spiro).

Tonight is the last in the series of Simon Amstell's dark, self-referential family sitcom. It's Mum's big day, not that you'd know it. Auntie Liz is busy making arrangements for her anniversary party: "I've written a really funny quiz from the internet." And Simon is fawning over his LA-bound actor boyfriend. Will Simon abandon his own career and accompany him to Tinseltown? Amstell never misses an opportunity to pre-empt critics with knowing jibes at his own self-absorption.

The final episode of Simon Amstell's gently hysterical sitcom finds him being forced out of the house, Auntie Liz declaring that "It's like a drug addict, you can't keep supporting them." Salvation, it seems, comes in an unexpected invitation to join the beloved Ben Theodore in Hollywood, although highlight of the night has to be Clive's rendition of "Sex on Fire".

Simon is set to appear on Radio 2 to promote his new play on Claudia Winkleman's show. That sets Grandma off on a critique of the Winkleman fringe ("Rrrgh, puts me right on edge... How can she see with such a fringe? It's dangerous, tell her.") Still, things are going quite smoothly until Auntie Liz arrives, whereupon Grandma's repertoire of things to offer houseguests at times of tension is put to the test.

This week, there are satsumas, Petit Filous and kitchen hardware ("What about a whisk? I've got two whisks!"). It's a lovely episode, full of painfully well-observed dialogue and cringe-making comic performances. Plus, the news that Clive is unexpectedly keen on Biffy Clyro.

Simon's new career as an actor continues to proceed like snakes and ladders. This week, everything seems to be on the up.

He's being ­interviewed on BBC Breakfast about his new play and after that he's going to be Claudia Winkleman's guest on Radio 2. But a jokey remark about another guest backfires and he's slithering down the snake of infamy once again.

The namechecks for actual famous people being mixed in with Simon's fictional family feels completely normal now. I love the idea, for instance, that Simon has borrowed a large sum of money from Derren Brown.

But as his auntie Liz demands that they finally get around to reading her father's will, most of this week's best lines go to Simon's mum, Tanya, played by Rebecca Front. After finally splitting up with Clive, she's decided she's off sex for good.

It's not the actual decision that's so funny, so much as all the colourful ways she and her family come up with to describe it.

Things are looking up for Simon Amstell's character as tonight's episode of this sterling sitcom opens. He's back on television, much to the relief of Mum (Rebecca Front) - "I wasn't sure how much longer I could keep paying my own mortgage" - an interview on Radio 2 is on the cards, and a windfall from Granddad's will means he can finally move out to Hackney ("I'm going to be a cool artist person"). Meanwhile Liz (Samantha Spiro) is planning a charity quiz and threatens to get Simon involved.

It's the penultimate episode of Simon Amstell's meta-comedy, which this week weaves his real-life Russell Watson incident - a joke on breakfast TV about the focus on the opera singer's tumour - into the plot. Simon's plans to move out suffer yet another setback, while Samantha Spiro continues to steal the show as hilariously grotesque Auntie Liz.

The fact that actor Geoffrey Hutchings sadly died in 2010 after the first series of this sitcom was made has been worked in gently, as the absence of his character, Grandpa, ripples through the plot. It affects Grandma most, wonderfully played by Linda Bassett. Her desperate refusal to acknowedge emotion - often changing the subject to offer someone fruit - is becoming more extreme. Last week we learnt that she has taken to stealing china pandas from friends' houses.

This week, things get worse as the marital problems of her daughter, the brilliantly horrible Auntie Liz, threaten to engulf the family. ("Do you want a melon?" quavers Grandma, desperately.) That gives scope for Samantha Spiro as Liz to chart the range of her hilariously shifty, two-faced character. It's her finest hour yet, a cringe-making masterclass, and very funny.