It has been 12 long years since James Corden was last on stage in a play, in his dazzling role in One Man, Two Guvnors . In the intervening time he has moved to the States and become an award-winning chat show host, but now he’s back and doing what he does so splendidly, displaying that impeccable comic timing in both word and gesture. He’s paired here with another supreme comic actor, Anna Maxwell Martin, celebrated as the frazzled (anti-)heroine of Motherland .

Yet Joe Penhall’s new drama delights in wrongfooting us, in subverting the expectations he so carefully crafts. When we first encounter Alec (Corden), he is in full-on Smithy-schtick, channelling his beloved character from Gavin and Stacey . He is fitting the new security system in the office of backbench opposition MP Monica (Maxwell Martin) and when Alec reminds Monica that they went to primary school together, it is all jovial recollections, even though we can see Monica quietly twitching to be rid of him in order to get on with her already overloaded day.

We settle back, more than happy to watch Corden and Maxwell Martin do what they do so splendidly, when matters take a sudden turn for the darker. Alec, a veteran of military intelligence in Afghanistan, reveals that he is going through an acrimonious custody battle with his estranged wife and wants to enlist Monica’s help in the fight. Monica, who likes to pride herself on her commitment to serving her constituents whoever – or whatever – they may be.