HHH Although it became an instant landmark on its first production in 1973, Peter Shaffer's play had never been revived in the West End until this production, originally starring Daniel Radcliffe, opened there last year.
Now it is on the road with Alfie Allen, another young actor whose film career has recently taken off with roles in Atonement and The Other Boleyn Girl, playing the teenager whose shocking and apparently inexplicable crime lies at the centre of the play, and Simon Callow as the self-detesting psychiatrist who has to unravel it.
It is clear from the outset that the teen-ager, Alan, is a bit of a weirdo - firstly because he has blinded six horses at the stables where he works and secondly because on his first appearance he prefers to sing TV jingles rather than engage in a conversation. What Dysart, the psychiatrist, gradually teases out is that the crime was the culmination of a disturbed adolescent's confusion of religious fervour and sexual frustration.
However, Shaffer tightens the dramatic screw by having Dysart - improbably, I think - see Alan's perverse but passionate fixation on horses as an indictment of his own emotional timidity.
Apart from Alan's taste in jingles nothing has obviously dated in the play (Shaffer has apparently updated some colloquial-isms) but the psychology seems glib, explaining everything and nothing.
Our attention is diverted from this by the famous device of having the horses played by actors.
Wearing open masks and standing on hooves, they perform a stylised impression of horsiness which is strangely disturbing and also introduces a distinct homo-erotic element.
The physical-theatre dimension was ahead of its time for the early 1970s. The severely simple set, with four wooden blocks serving as both the stable and Dys-art's office, is by John Napier, who designed the original production, here working with young director Thea Sturrock.
In a demanding central role which comes close to being a monologue at times, Simon Callow makes Dysart as believable as I could imagine him being. Alfie Allen is also very good as the initially baffling and later too transparent Alan. Altogether, it's an undeniably intense but not very pleasant theatrical experience.