In a company full of young people doing dull office jobs, the staff are all trying to establish their lives, to get ahead, and to get into each other’s pants. It’s a situation as old as the shorthand/typist, but these days, as first-time playwright Jason Charles has grasped, there are potential new twists.

Gay workers are increasingly likely to be “out” at work, and their colleagues are going to have to come to terms to working, and socialising, and even getting changed in the same dressing room, as them.

That’s the situation at the start of Steam, which opened tonight at the White Bear Theatre in Kennington. Matt (Oscar Wild), the self-proclaimed office alpha male, who treats his girlfriend Vanessa (Lusia McAnespie) with scant respect, is horrified to find that for a football match against their deadly rivals in the crate-hire business, she’s enlisted a quiet, serious, and gay, member of staff, Luke (a finely judged, subtle performance from Daniel Kanaber). One of Matt’s more repeatable names for him is “fairy-cakes”.

The team grows by one with the arrival of Chris (Glynn Doggett), who’s also straight. He seems young, and vulnerable, and you wonder what he might be dragged into by this dominating character until the numbers are evened up with the final member of the “team”, Billy (Jonathan Gibson), the office junior. He’s as camp and over-the-top as could be imagined, and has a fine line in sexy song-and-dance routines.

There’s time for a few nice one-liners: “I had a promotion but it is not a lobotomy”, says Matt. “I don’t usually associate loving with Ronnie Kray,” says Luke, after walking in on some of Matt’s “rough wooing” of Vanessa. But the play is a bit slow to get started. Will there be an all-in brawl? you wonder.

No. Instead, a curious sport develops – the competitive telling of what Matt identifies as NQEs (Near Queer Experiences). For a homophobe, Matt is curiously happy to talk about gay sex and gay life. And he seems oddly keen to touch, even if it is often a punch, the apparently vulnerable Billy.

But what about the football? Well, there is no game – at least not of that sort, for, it emerges, there’s a lot more to this Friday after-work gathering than that. And there’s a lot more to this apparently prosaic locker-room than meets the eye.

I won’t set out what, for after a slow first 20 minutes, the twists come thick and fast and the conflict develops at a brisk pace. The inner tortures behind two kinds of bombast – the camp and the crass – start to emerge, indeed sometimes to crash out.

Charles has a strong academic background in playwriting and it shows – Steam’s structure is neat and nicely balanced, even if he occasionally struggles to get his characters on and off stage with the naturalism the set-up otherwise demands. He has a fine ear for dialogue, and for all the sex talk the play is never crass.

The director, Tonia Banks, has also done a good job of keeping down the historionics – tears will be shed, and much body contact made – but none of it is overdone, or drawn out to the point where you’re forced to gaze at the ceiling.

All in all this is a classy, entertaining evening of fringe theatre that deserves rather more than the one-week stretch that it has now booked at the White Bear. Not one for the metaphorical maiden aunts, but a good laugh for any other audience.

Steam continues at the White Bear until Sunday. The play runs for 70 minutes with no interval.