There can be no doubt that Nicholas Hoult is all grown up now. This engaging 19-year-old, who first came to our attention as lovable Marcus of the pudding bowl haircut in the Hugh Grant film About A Boy, strides confidently onto the stage in his West End debut performance and starts talking about female genitalia. It’s the sort of thing Tony, his character in the hit Channel Four teen drama Skins, might have done.

As a star vehicle for Hoult, New Boy is ideal. It’s generally amusing, occasionally risqué and always daft, and doesn’t ask a huge amount either of him or his artfully startled hair. Instead, he can lollop about in his appealingly natural manner, showing increasing touches of Grant himself as he plays Mark, a sixth former who manages nerdiness and would-be cool at the same time.

Adapted from William Sutcliffe’s novel by director Russell Labey, New Boy whizzes us through a hectic two years of sexual confusion and coming-of-age. Mark’s initial scheme is to befriend good-looking newcomer Barry (Gregg Lowe) in the hope of some second-hand cachet, and from there on it’s a riot of horny French teachers (a cherishable cameo from Mel Giedroyc) and sultry sisters, with some unconvincing homophobia thrown in for good measure.

We’re obviously not supposed to notice that Hoult is by far the most alluring person onstage when he says of Mark: “This is a books face, not a sex face,” the ripple of disagreement from the young women in the audience is almost audible. On the downside, the script veers towards the fliply arch and casually misogynistic, with more lurches in tone and storyline than in a teenager’s hormones. The “f**k” and “Jesus Christ” counts reach the several hundreds, and these hyper-articulate teenagers, complete with a subordinate clause for every occasion, are of the sort that tend to crop up only in fiction. When we eventually reach some dark places, Labey’s peppy production finds itself flailing in the shallows.

Still, it’s a good 90 minutes of theatre from Hoult’s point of view, and the possibilities before him seem abundant. Let’s hope that he opts for serious acting, rather than hair-flicking.