Thoroughly Modern Millie has become forever associated with Julie Andrews, and her presence in the original 1967 film doubtless meant that sniping critical comments like “initially most agreeable, but subsequently patchy 1920s spoof” had little effect on box office takings. The story features Millie Dillmount, who abandons small-town Kansas for life in 1920s New York. Once there, Millie takes up residence in Mrs Meers’s dodgy hotel and associated Chinese laundry — laundry baskets are very useful for smuggling out drugged guests, girls who thought they were going to become Broadway hoofers. In fact, Mrs Meers is selling them into the white slave trade. None of that for Millie, however: she takes a job in the splendidly named Sincere Trust Insurance Corporation, and sets her determined sights on marrying the boss.

In 2002, the film was adapted as a Broadway show. Ten years on, the stage version of Thoroughly Modern Millie is the Watermill’s summer musical choice. To be honest, I was not expecting much: the show is as patchy as the film, and quite a lot of Jeanine Tesori’s music can go in one ear and straight out the other. Having done so many successful musicals in the past, had the Watermill started to reach the bottom of the barrel?

But all doubts vanished within seconds as the 12-strong, all-singing, all-dancing, and — as usual at the Watermill — all-musical instrument-playing cast launched into the flapper-style opening number with a pulsating rhythmic beat. The score may be no great shakes, but who cares when it’s delivered with such energy and style? And talking of style, director Caroline Leslie (also responsible for the Watermill’s highly acclaimed Radio Times, which tours to the Oxford Playhouse next month), musical supervisor Paul Herbert, choreographer Alistair David, and designer Tom Rogers have put together a fully unified production that absolutely breathes style and 1920s atmosphere. Typical of the attention to detail are the period silent film captions that provide English translations as Mrs Meers’s Chinese laundrymen (Dexter Galang and Benjamin Wong, an inspired comedy duo) argue and bungle her instructions.

Hotel proprietor Mrs Meers herself (Amy Booth-Steel) comes close to stealing the show — with a leer, an elaborate wig, and a strangulated Oriental-New York accent, she is the ultimate in Mikado Katishas. But no one could beat Eleanor Brown as a radiantly smiling, yet thoroughly determined Millie — this is the performance of a star in the making. In support, Helen Power as Millie’s country-girl friend and Paul Matania as Millie’s lantern-jawed boss are particularly memorable. But this is a first-class ensemble production that triumphantly enhances its original script and score.

Until September 22. Tickets 01635 46044 or