The Boy Friend, Open Air Theatre, Regent's Park, London <br/> The Hot Mikado, Watermill Theatre, Newbury

A love note to the Twenties, Sandy Wilson's musical of 1953 has been given an equally loving production by Ian Talbot, full of girls in sugar-almond-coloured frocks and ruffled bathing costumes. Wilson's tribute, written when the world, like that of the Twenties, was trying to forget a war of unprecedented horror, retains our affection for its infatuation with the period.

Polly Browne's English chums at her Riviera boarding school rally round when she suffers boyfriend trouble - the headmistress brings her long experience of l'amour to bear, and the school's maid cheerfully agrees to turn a blind eye to rule-breaking. The cast maintain high spirits without slipping into mockery, and the mood of the one sorrowful scene, in which Polly, hurt and confused, thinks her sweetheart has lied to her, is beautifully handled.

Steven Pacey is too young for the role of the heavy father and too boring for words. Rachel Jerram admirably personifies the wide-eyed, peppy Polly, and Summer Strallen is a tonic - with plenty of gin. Jennifer Piercey is perfect as Talbot's censorious wife, wielding a monocle as deadly as a battleaxe. It is true that the show is too long, with too many and too similar numbers, but, to quote Mae West, "Too much of a good thing can be wonderful".

Eleven years ago, London was given a treat - an exuberant production of The Hot Mikado, Rob Bowman and David H Bell's reconstruction of the 1939 show in which a black company made Gilbert and Sullivan hep to the jive. Sadly, this terrific show, with zoot-suited courtiers brandishing fans like flick knives, met with public indifference. It has now been given the Watermill treatment of using actors who can not only sing and dance but play musical instruments.

The production has also been "youthified", a step that means adding lines and business ("You piss me off!"; little maids who fondle their pubic mounds while smirking at the audience) in contemporary style.

The result is not only coarseness but monotony, as the show's moments of unexpected, transcendent beauty are trodden into the general murk. However, the energy, if at times misguided, maintains a high level, and the musical and vocal skills are higher still.

'The Boyfriend' (0870 060 1811; www.openairtheatre.org) in rep to 9 September; 'The Hot Mikado' (01635 46044; www.watermill.org.uk) to 2 September