Sean Foley, The Rep’s soon to depart Artistic Director, has a penchant for movie adaptations (The Ladykillers, Mean Girls, Minority Report) and fervent fanbases (The Way Old Friends Do), so putting on - and in this case helming - a stage version of one of the UK’s biggest cult movies is perhaps no surprise.

It’s a great way to get bums on seats of course, but a risky venture nonetheless, and the sort of endeavour for which the expression ‘hiding to nothing’ was invented. Serious aficionados might turn up, but make for tough taskmasters, not least because they’re so familiar with the source material they can probably quote the dialogue better than the actors.

Mercifully someone else who knows the original rather well is its creator, Bruce Robinson, and he’s the one behind this brand-new stage adaptation, which is premiering in Brum as a Rep Original but will almost certainly end up in the West End.

In fact it’s pretty much guaranteed to do so on the basis of this performance, and the audience’s ecstatic response to it. From the opening scene everything feels just right – the mood, pacing, staging (the niftily quick-changing set both minimal and expansive), music (performed by a live band) and spirit are all right on point. As are the performances, with Robert Sheehan, Adonis Siddique and Malcolm Sinclair all hugely impressive as Withnail, Marwood (aka ‘I’) and Uncle Monty respectively. No mean achievement given what a character-driven piece it is, and how intrinsically linked the roles have become to the film’s stars Richard E. Grant, Paul McGann and Richard Griffiths.

In case you’re unfamiliar with the original, it’s character-driven because the flimsy storyline borders on inconsequential. Set in 1969, the narrative, and I use the term lightly, revolves around a pair of self-centred slacker actors who head to the Lake District to get away from their squalid London flat and failing acting careers. And that’s more or less it. The pair talk a lot, drink a lot, smoke a lot (of pot), meet a few people and get into a few minor scrapes. Oh, and Monty becomes infatuated with Marwood. Chekhov this emphatically is not, although one of his works does get a namecheck.

Ridiculous booze-fuelled situations and endlessly quotable dialogue are the order of the day here, and while the comedy is largely puerile (though the actors never seem as smashed as their screen predecessors), there’s a huge whiff of the film’s devil-may-care attitude and originality, the latter especially evident in Alice Power’s fabulous production design.

Fans of the movie will lap it up - many of the audience were laughing at lines before they were delivered and even cheered some of the classic quotes - but there’s something here for first-timers too, and the show makes a terrific finale to Foley’s tenure at the venue. He’s definitely going out on a high.

Four stars

Reviewed by Steve Adams at The Rep, Birmingham on Tuesday 14 May. Withnail and I continues to show at the venue until Saturday 25 May.