The well-regarded playwright Simon Stephens was in Oxford on Tuesday for what he can hardly fail to have judged an adroit production, under director Joe Murphy, of his 2008 Edinburgh Festival hit Pornography.

This dark-hued drama is widely considered a shocker. This is not as a consequence of what is implied by its title — though a strong sexual content cannot be denied — but for its attempt to make understandable, if not excusable, the motives of one of London’s 7/7 bombers.

Heading south by train on his deadly mission, this articulate mass murderer (Tim Kiely) surveys the shoddy state of the country and its occupants — the overdressed, over-fed “little pigs” of children particularly wrankle. Then he spits: “If I had the power, I would take a bomb to all of these.” He has, of course, both power and bomb.

How are we to compare his attitude with the murderous fantasies of psychopath schoolboy Jason (Chris Greenwood), consumed with lust for his teacher Lisa (Anna Maguire)? Only, perhaps, to hope that his remain merely fantasies.

Whether one does, or does not, venture into what might be considered the unthinkable is a major theme of the play. This is seen most obviously in the passionate affair between an upper-crust young man (Max Gill) and his sister (Charlotte Salkind) — which rivals in intensity the incestuous relationship in John Ford’s ’Tis Pity She’s a Whore.

It is there, too, in the octogenarian woman (Mary Flanigan) drenching herself in Internet porn, and the elderly professor (Rory Fazan) making a move, almost a rape, on a former student — Lisa again.

Yes, characters connect; words and ideas also link them — the music of Pink Floyd, foodstuffs, scents, haunted houses, London as a city of the dead, or soon to be so.

The bomber’s mission south had resonances, as I watched it, with the progress by rail to the same London destination in Philip Larkin’s The Whitsun Weddings. This was partly on account of the precision of the language used to describe it. It seemed oddly appropriate, then, to be told as Tuesday’s uniformly well-acted performance ended that Stephens would be giving a question and answer session on the play in a lecture room named for Larkin at his old college, St John’s. A “frail travelling coincidence”, indeed.

Pornography continues until Saturday. 01865 305305 (www.oxfordplayhouse.com).