The Open Air Theatre has a special enchantment that makes it the perfect place to introduce children to the theatre. Its steeply raked seating gives everyone a good view, and in this mysterious woodland setting even the inevitable rain seems exciting, as the audience wriggle into plastic ponchos in unison.

So it's a great setting for this season's Twelfth Night, re-imagined by director Max Webster for anyone aged six or over. Although the play has been trimmed and some scene-setting explanations very sensibly added at the beginning, this is otherwise a faithful and very entertaining show that has enough comedy, music and imagination to keep its young audience gripped, and more mature members happy too.

The calm and assured Iain Johnstone takes on the warm-up, requiring Mexican waves and seaside sound effects from the audience to create the storm scene that opens the play – the perfect way to engage and energise everyone in the house.

Johnstone is a strong presence throughout as Feste and Antonio, and he's also the composer, contributing beautiful vocal and instrumental performances and presumably arranging the ensemble musical numbers that punctuate the show so effectively.

The unsympathetic Malvolio is played as a Yorkshire prig by Nick Malinowski who deservedly gets some of the best laughs for his preening, cross-gartered pretensions. He doubles up as Duke Orsino, puzzled and disturbed by his feelings for Sarah Ridgeway's chirpy, adoring Viola.

Guy Lewis also shines in his two contrasting roles – upright Sebastian and foppish, new-romantic Sir Andrew Aguecheek, whose huge, bobbing hairpiece gives him the look of a foolish young poodle in need of a trim.

Riann Steele is a beautiful, dignified Olivia; Wayne Cater staggers, belches and makes trouble very creditably as Sir Toby, and Maria's saucy wit and charm are captured by Vera Chok, whose lovely singing voice adds power to the ensemble songs.

Designer Ben Stones has excelled himself with the set, in particular the huge love-o-meter that lights up and rings a bell whenever anyone is falling in love, which is pretty frequently. A sunflower theme is evident throughout, though it's never entirely clear why, but who cares – they're beautiful flowers and double up very nicely as props. And for a show aiming to appeal to children, making super-soakers the weapons of choice for the fight scene is inspired.

This lively, accessible Twelfth Night makes a great outing, and the music is a particular strength. It's not often you'll hear a seven-year-old humming the final song to herself as she leaves the show, but that's what happened here.