The Birthday Party review – Jane Horrocks hosts in a house of horrors

Harold Pinter’s first full-length play was a flop in 1958: “Oh, you poor chap,” an usher consoled him amid empty seats.

What repulsed early audiences and most critics was unsolved puzzles. The solid setting of a seaside boarding house holds people with shifty foundations. Is Stanley, the long-term lodger of landlady Meg and deckchair attendant Petey, actually a former concert pianist? When a gangsterish duo checks in to check out Stanley, why does Goldberg have three different first names (Nat, Simey, Benny) and is sidekick McCann really both a former IRA terrorist and defrocked Catholic priest?

The Ustinov Studio is a compact and convivial space, encouraging interval discussion, with my fellow audience members wondering whether some characters exist only in the memory or fears of others, or were previously together in a mental health institution, secret society or cult. These responses are all legitimate because democratic ambiguity of interpretation – for actors and audiences – is key to Pinter’s greatness. One viewer said it reminded them of Inside No 9 – indeed, the current popularity of macabre surrealism is why Pinter, as his birth centenary approaches, remains a writer for our times.

Richard Jones’s direction emphasises the horror, a sequence in which party games are played by torchlight in a power cut drawing to mind The Shining. With lights up, the set and costumes by Ultz , exaggerating a documented aspect of 1950s Britain, double down on brown, the sole colour of walls, chairs, suits and shoes, and patterned into shirts and dresses. When Meg and perky neighbour Lulu don evening frocks for the titular celebration, the effect is (reflecting a line in the play) of lurid tulips bursting through soil.

In the potentially stereotypical roles of unexpectedly libidinous women, Jane Horrocks’ Meg and Carla Harrison-Hodge’s Lulu suggest explanations in past damage. As Stanley, Sam Swainsbury radiates instability through a vocal range from shouts to silence and sudden clutches of his temples hint at possible past ECG treatment. As Goldberg and McCann, John Marquez and Caolan Byrne can be terrifying but crucially also have moments of terror. In what can be the token husband role, Nicolas Tennant plays with the riddle of how much Petey knows and relishes the pivotal anti-authoritarian line: “Don’t let them tell you what to do!”

There are two references to a “caretaker”, previewing the title of the 1960 masterpiece that saved Pinter’s career. But most dramas still don’t hold a candle to The Birthday Party.

• At Ustinov Studio, Bath , until 31 August