It’s a crying shame this thrilling 1964 play by Christopher Hampton, written when he was still a teenager, has gone unseen for so many years.

Not least because it contains in central protagonist Ian a character to rival Jimmy Porter, Mr Sloane and Alex in A Clockwork Orange as a role to put a young actor on the map. And this production certainly does that with former Harry Potter star Harry Melling.

Ian is an 18-year-old with a vocabulary and a sensibility way beyond his years. In verbal spars with bedsit-mate Jimmy, he reveals a rapier wit and a crippling combination of sexual assuredness and confusion, aiming his teenage frustrations at the extraordinarily ordinary Dennis.

His unreciprocated passion soon finds an outlet when Jimmy’s attractive young mother comes for tea. As lost souls compelled by a near-Oedipal urge, the unlikely couple soon begin an affair that is to have devastating consequences.

It’s easy to see why this play caused such a sensation when it first appeared. The fact it was written by an 18-year-old is almost laughable considering its maturity, and Hampton certainly holds his own when compared to other giants of the period - Osborne, Orton et al - showing himself as a young writer with his finger bang on the pulse of the sexual revolution.

In the central role, Melling – who has slimmed down considerably from his days as Dudley Dursley – is nothing short of a revelation, coming over like a brasher Alan Bennett with his working class sagacity, NHS specs and fondness for armchairs.

The one-liners come thick and fast. Lamely going about some household chores, Jimmy asks Ian if he’s ever going to dust. “We all are” he fires back.

Melling is ably supported by Sam Swainsbury as his socially superior roommate and Abigail Cruttenden as his tragically undersexed mother. Director Blanche McIntyre has teased the very best from her young cast, and gives the play the unfussy, faithful revival it richly deserves.