The World's Biggest Diamond is not a play for old lovers – though it might be for those who like their theatre intense and chamber-like. Few may have heard of writer Gregory Motton. Even in the Eighties when he was beginning to make his way, his subject matter – tramps, those on the edge of society, the emotionally crippled - and oblique dialogue, didn't always find favour. To this viewer's eyes at least, he was a latter-day British Gorky though more often parallels were made with Samuel Beckett.

Spurned by these shores, Motton went on to become a hit in Europe, especially France, and a notable translator of Strindberg. The latter seems especially pertinent with this latest, Motton's first play at the Royal Court for over ten years. It’s a duet in which two former lovers - one dying, the other briefly come to care for him - go over old ground picking at their mutual resentments like two prize fighters slugging it out until one of them drops. Similarities with Strindberg are obvious.

Motton's circularity and the insistence of a vision which ultimately sees each character trapped in a love-hate relationship of sado-masochistic proportions is vividly reminiscent of Strindberg's Dance of Death. Even Anthony Lamble's hermetic room, shadows playing on the walls and the insistent rumble of surf carries the same sense of isolation of the tower in which Strindberg's captain and his wife bicker and snarl their way to stasis.

All of which could be irritating were it not for the depth and intuition Motton brings to his analysis of the dying man – antagonistic, regretful, frightened – and the contrasting (and contrary) dignity with which he endows his younger female protagonist.

One might have longed for a bit more diversity from Motton – there's an unseen husband in the background, a cleaning lady and some neighbours next door, known disparagingly as `Chummy' and `Chummy'. But Motton appears uninterested. His sole focus remains and our joy becomes – if joy is the word for such a baleful, astringent contest – watching Jane Asher of all people going 12 rounds with that wiliest of actors, Michael Feast.

As Mr Thomas, Feast gives a beautifully nuanced performance whilst Asher reveals previously untapped depths in revealing the hurt beneath her habitual well-groomed veneer. Perfectly matched and watchfully directed by Simon Usher, you may not like the truths and longing for a perfect love in a lonely universe Motton lays bare. But it makes for a compelling 90 minutes.

- Carole Woddis