The Unfriend: the laugh-out-loud tale of a decidedly terrifying interloper

It’s a brave or foolhardy critic who endorses or condemns a comedy without reference to the sounds emanating from the audience around them, or indeed from their own mouth. At Chichester last May, the Minerva was filled with vocal evidence of mirth, including my own, at The Unfriend, the stage debut of renowned TV writer Steven Moffat: compelling validation for a work whose main object is entertainment.

I duly raved, but there was still the nagging thought: am I – and the other approvers – a bit mad, or easily pleased? The show’s transfer to the West End offers no small measure of relief and reassurance.

Here again unfolds a Dahl-esque tale of a brash American widow befriending an uptight middle-class couple on a cruise and then materialising at their London home, the need to dislodge the visitor from their family nest maximised by the discovery, just before her arrival, of online evidence suggesting that she’s a serial killer. And here again, with the original cast intact, is laughter, erupting continuously throughout Mark Gatiss’s impeccable production.

To be blunt, the play is no snob hit. It’s done with great craft but little overt sophistication. Sitcomish, it’s not above a running joke about breaking wind and stoops to lavatorial humour. The funny thing is, though, that the chance of being unsure whether its insightfully daft or indulged nonsense marries with the tease contained within the story itself.

Is Elsa Jean Krakowski a vivacious monster – responsible for the poisoning of her nearest and dearest – or unlucky and misunderstood? The couple – Reece Shearsmith’s Peter and Amanda Abbington’s Debbie – are undone by their own British politeness as they try to force her out, and also driven to distraction by the lack of firm proof.

Elsa by turns denies and shrugs off culpability while dropping in cavalier references to life and death. And that effusive and casual attitude is what the pair’s emotionally neglected teenagers (Gabriel Howell’s Alex and Maddie Holliday’s Rosie) respond to – the more their folks shield them from the wayward interloper, the more they want her to stay. There’s a political insinuation – Elsa is a Trump-loving “disruptor”, who disdains facts – but above all she’s a catalyst for domestic transformation (“She’s Murder Poppins!” Debbie wails).

So, at one level, the evening is the height of contrivance, and part of the pleasure derives from seeing the effort the cast put into making it all work, ensuring that every conversational beat, gag and physical tic is spot-on, from the oeillades of Frances Barber’s rasping, larger than life mischief-maker, past Shearsmith’s manically exasperated family man – hands darting and head bobbing like a demented organist – to Michael Simkins’s hangdog fixity as the continually ignored and terminally irritating neighbour.

As an aside, I’d still love there to be a bit more contemporaneity scattered into the dialogue  – we’re not quite in the “woke” here and now, and more depth to the characterisations wouldn’t hurt. But peer hard enough and you’ll glean that the piece is founded on a robust truth about human contrariness. At a time when nuance seems doomed, what a glorious breath of fresh air to see the lightest-touch dramatic argument posit that people can be, yes, both terrible and wonderful.

Booking until April 16. Tickets: 033 33 202 895; theunfriend.com