YORK Opera seems to have slipped into the pattern of staging a Savoy Opera every other year. We are all beneficiaries. There are a number of natural comedians in their ranks whose talents are just what Gilbert & Sullivan requires.

But there is another, sometimes overlooked, card up this company’s sleeve. In this new production of Iolanthe, it is Alasdair Jamieson’s orchestra that does much more than keep the show on an even keel. Jamieson everywhere finds that extra sparkle or emotional tinge that provides greater depth and colour. When the Lord Chancellor is squirming in his bedclothes, or the fairies are prancing, the instruments virtually do it for them. The singers clearly feel the orchestral support.

Like all Pauline Marshall’s productions, the devil is in the detail, not just the instruments. It is a dangerous tactic – you must never allow your chorus to fiddle about when a principal is wrestling with an aria – but it works here. For Marshall is an expert. So she imports a couple of sheep (Anna Robinson and Olivia Robinson), whose reactions are hilarious, not least when they are blown over by an unexpected revelation.

Another unusual ploy is to dress all the fairies differently. All have wings, but otherwise they have names and are dressed accordingly. Maggie Soper’s costumes are wildly varied, though she wisely sticks with sumptuous ermine and velvet for the peers. Her set, movable flats apart from a small bridge from which principals announce themselves, gives us giant bushes, flowers and toadstools. The backdrop changes for the House of Lords. It works well, allowing the large chorus plenty of space for their antics.

Cathy Atkin is a constantly engaging, youthful Iolanthe, always musical. Jasmine Caine as Phyllis has an especially bright tone at the top of her soprano which she uses intelligently: with sheep in tow she is a Bo-Peep lookalike, suitably Arcadian. Her Strephon is the lively Michael Foster, who could focus his movement more: he tends to look nervy. But his potential is palpable. Rebecca Smith is an impressively statuesque Queen of the Fairies.

John Soper’s bumbling Lord Chancellor is a model of clarity in his patter-songs and witty in his reactions. Ian Thomson-Smith uses his fine baritone to excellent effect as Mountararat. Hamish Brown’s Tolloller partners him well, though his tenor tends to sound pinched under pressure. Steve Griffiths milks Private Willis’s aria to the utmost with doleful irony.

The chorus is musically very well-drilled, the men sounding particularly robust; its choreography needs a touch more discipline. But the laurels must go to the superb orchestra, which is taut and agile from start to finish.

Further performances today at 2.30pm and 7.30pm; box office (01904) 623568.