At first you think that Anthony Neilson has written A Christmas Carol II. It’s Christmas Eve, and Scrooge has turned into as fanatic a merrymaker as he was a miser and is driving the Cratchits mad with his practical jokes and pushy generosity. So paternally has he been behaving to Tiny Tim that poor Bob feels he has become a second-class father and steels himself to tell his chortling, snowball-throwing boss that, no, this year he isn’t wanted for Christmas lunch.

It’s a mischievously entertaining opening to the play that Neilson himself has staged with an all-RSC cast but, like some other episodes, it leaves one asking how much it contributes to the piece’s meaning. It’s a question not wholly answered by the next scene, which introduces us to Brian Doherty’s Brian Wilkins, a producer of reality programmes such as Chimps in a Monastery and a self-pitying, self-hating drunk whose estranged wife won’t let him talk to their daughter on, yes, Christmas Eve.

Well, it ensues that, as in Dickens’s original, he’s visited by three spectral figures, one of them Sean Kearns’s Scrooge, another his rough old father, the third a British soldier killed by mortar fire in Basra. Gradually a point emerges. As his Dad says, Brian is a mediocrity who has been squandering his life on trash. He’s even acting out the role of an oversexed woman on an internet porn site. One of his friends at the local Alcoholics Anonymous meeting clearly believes that Brian was made in God’s image – but, as he himself says, he’s “a god in ruins”.

Does Brian, like Scrooge, get a chance of redemption? That depends how seriously one takes the dénouement, in which he parties with cartoon punks from the computer game Second Life, with his daughter transformed into an Ulster male. Speaking for myself, it left me unsure of anything except that Neilson hasn’t lost the odd, disturbing imagination he displayed in Penetrator and The Censor.

And there are enjoyable moments en route to that ending: that AA encounter group, with a pretentious leader earnestly inviting the topers to become child abusers, this time of the “child within”; one kid arguing to another that it’s best to keep potentially ungenerous parents thinking you believe in Santa; a hilariously topical conversation about whether you have to be a suicide bomber to be a serious Muslim. Fragmentary? Yes, rather – but lively too.

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