An alternative title for Tom Kempinski’s play Duet for One might well be Duel for Two as far as Robert Harford’s new touring production goes, for the violinist and psychotherapist whose professional relationship is under dissection clash continuously. She has been a much-lauded, world-class performer but is now debilitated by the onset of multiple sclerosis. He knows from bitter experience that some psychological conditions are beyond human aid.

It’s been subtly altered and updated from the original version which I remember from London in 1980; I recall in particular a bleaker, more abrupt ending. Michael Holt’s set is a spacious one, of which Stephanie Abrahams’ wheel-chair can take full advantage. The formality of the room with its carefully chosen, accurately positioned furniture reflects Dr Feldmann’s own attitude to his patients.

Words are the matter of the drama, words and the meanings behind them. Keeping our attention engaged is matter for the performers. Haydn Gwynne gives Stephanie the arrogance which goes with a consciousness of abilities outside the normal. Her entire world is crumbling, not just her body, and she can only rage against it. This comes over clearly to command understanding and sympathy as well as irritation.

In many ways, Feldmann is the more difficult role. William Gaunt makes him deliberately low-key, a man dedicated to helping others and finding that assisting those who refuse to follow his prescriptions perhaps more draining than he is prepared to admit. Considered of speech and never abrupt in movement, you sense why this patient interests, concerns and aggravates him. Director and actors alike take the spiral of the action to its ambiguous conclusion with sincerity and commitment.