The problem with creating a play about Boris Johnson is that it reinforces his inflated sense of his own importance. Jonathan Maitland’s topical satire has a few good gags and sharply improves in its futuristic second half but, while suggesting that Johnson is a vacillating opportunist, it leaves its subject unskewered and adds to the media infatuation with a so-called “character”.

Maitland’s first half takes place at a dinner party chez Johnson in February 2016 when the host was pressed into making a decision, not least by Michael Gove, about his attitude to Europe. Unlike Steve Waters’ Limehouse, which dealt with a similar gathering leading to the formation of the SDP, the play tells us little new. There is a good deal of functional dialogue on the lines of “Dominic Cummings? Isn’t he the mastermind of the Leave campaign?”

Johnson’s visitation by the spirits of Churchill, Blair and Thatcher – who, despite being a passionate advocate of the single market, improbably screams “I want you to leave Europe now” – also falls flat. The best joke is at the expense of the Russian proprietor of London’s evening newspaper, who is portrayed as an unconscionable name-dropper.

Facebook Twitter Pinterest Visitation ... Arabella Weir (Winston Churchill), Tim Wallers (Tony Blair), Steve Nallon (Margaret Thatcher) and Will Barton (Boris Johnson). Photograph: Pamela Raith

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The play picks up in the second half, which takes place in 2029. It would be a pity to spoil all the surprises but the hero, now presenting The Apprentice on television, is invited to stand for the fourth time as prime minister and secure Britain’s re-entry into Europe (or “Brentry” as it becomes known). This is amusing for a while, but even here the joke about Johnson’s familiar failings runs out of steam and the funniest gag in Lotte Wakeham’s production is a visual one lifted straight out of a Buster Keaton movie.

Will Barton, though he lacks the physical girth, gives a perfectly plausible imitation of Johnson and there is good support from Steve Nallon who, as in Maitland’s Dead Sheep, plays a hectoring Thatcher, and from Tim Wallers who captures Blair’s scoutmaster enthusiasm. But the main conclusion is that Maitland’s mind-changing hero is not nearly as interesting as he thinks he is.