‘Don’t touch yourself anywhere while on camera,” instructs the producer. Auditions are under way for the Corny Collins teen dance TV show. The latest crop of hopefuls have nearly all been selected when Tracy Turnblad puffs in, worried that she has missed her chance to shine. “You’re not too late, dear,” snaps the producer. “Just too much”.

Thus begins Scott Wittman and Marc Shaiman’s musical Hairspray. The year is 1962, and The Corny Collins Show is based on a real show transmitted from Baltimore at that time. It soon becomes apparent that Corny Collins’s producers are not only biased against fat people like Tracy, racial segregation is rife too — there’s a ‘Negro Day’ once a month, as opposed to a ‘White Day’ every day. Tracy is, however, no wilting violet, and is determined to break through every prejudice.

All of which could make Hairspray a preachy, worthy affair. But it isn’t like that at all — this is a feelgood show, which carries its storyline with wit, robust style, and a profusion of smack-you-in-the-eye costumes. The serious message is carried in moving numbers like I Know Every Step, sung by Tracy and black Corny Collins applicant Inez (Seliza Sebastian, who could well be a star in the making).

Laurie Scarth plays Tracy as if she was born to the role. Short and round (although, of course, this may be due to judicious padding), she fizzes round the stage like a bouncy ball attached to a firework. Her crusading spirit is never in doubt. But she’s a slip of a thing compared with her Mom (Brian Conley, in a hugely enthusiastic performance), who is initially unenthusiastic about Tracy’s showbiz ambitions — it’s her Dad (Les Dennis) who backs her from the word go. Messrs Conley and Dennis studiously avoid camping it up, but came close to collapsing with the giggles while relishing their big romantic duet Timeless to Me — much to the delight of the audience.

Design (David Rockwell and William Ivey Long) and score (Marc Shaiman) are infused with authentic 1960s atmosphere — the music is a joyful reminder of the varied pop scene immediately pre-Beatles. The whole show is delivered with tremendous verve and split-second timing — if Jerry Mitchell’s choreography sometimes seems a bit samey, who cares?

My only regret was that some comedy gems may have got lost in the quick-fire dialogue delivery. Among the nuggets I picked up, I particularly relished: “Don’t tell me Liberace has found the girl of his dreams”, and “Eva Marie? Ain’t she a Saint?” Milton Keynes until October 9. For tickets call the box office on 0844 871 7652 or go to www.ambassadortickets.com/miltonkeynes. New Theatre, Oxford, from October 12-20: 0844 847 1585 (www.newtheatreoxford.org.uk).