The Mikado, Charles Court Opera, King's Head Theatre

Is this the year that G&S became definitively chic again? The slow-burn effect of ENO's "Miller Mikado" and Mike Leigh's Topsy-Turvy now results in numerous fringe benefits. Sasha Regan's all-male Union Theatre regime has delivered its best yet - Iolanthe at Wilton's Music Hall, the most touching and funny show I've seen over the last 11 months - and now Charles Court Opera gives us more witty operetta-in-close-up with a cast of nine backed up by two pianos.

The voices are all in better, youthful nick than you ever used to get in the bad old heyday of D'Oyly Carte, but there's one performer who rivets all attention. It's apt that Pooh-Bah is the Lord High Everything Else of the Titipu court - more Westminster than Kyoto, as Jonathan Miller first proved to us was Gilbert's intention - since John Savournin, incarnating him as a scion of public-school privilege with an arching left eyebrow that people should travel miles to see, not only steals the show but also directs it.

From the first, pianola-precise pentatonics of the Eaton-Young Piano Duo, we know the pace is in safe musical hands

Since Savournin's brilliance is to deliver the lines of that very superior personage with a natural patrician ease that would even put Stephen Fry to shame - as well as to sing them with a baritonal assurance that suggests he'd be the perfect young Mozart Almaviva - it's baffling why he didn't make sure everyone in the cast also left the extra work to the topsy-turvy text. The minute Lord High Executioner and cheap tailor Ko-Ko makes his entrance, backed up by a court of three, you know Philip Lee's Common Little Man accent is going to be wearing.

His is an unusually well-sung, tenor Ko-Ko, and blends well in the most impressively staged number in the show, the witty 'execution' trio with Pooh-Bah and Pish Tush. Yet his "little list", delivered as originally written without the usual Richard Suart-style topicalities, falls a bit flat and until we get to the sublime tragicomedy of the "Tit-willow" ballad - was there ever a more sublime blend of calculation and pathos, humour and wistfulness? - and the raucous duet with Rosie Strobel's vivacious Katisha, you want to shout out that less would be more. Same applies to Susan Moore's Pitti-Sing, a face made for comedy, but she too needs to realise that Gilbert's wit and the extremely close quarters of the King's Head mean she doesn't have to work overtime for the laughs.

Otherwise, the casting is shrewd. Kevin Kyle's Nanki-Poo is a rather sweet busker-minstrel, the only one of the work's characters who doesn't seem to be consumed with self-love, and his red trombone comes in useful not just for discreetly adorning his great solo but also for fanfaring the Lord High Executioner. The maidens, shorn of their introductory chorus, seem costumed from a different show with their Japanesey raven-hair bobs and do the usual business well (pictured right); Catrina Kirkman's Yum-Yum falls an inch short of softening charm, but phrases "The sun whose rays" with canny, affecting musicianship, and it's nice that Caroline Kennedy's Peep-Bo gets more than her usual third-fiddle role when "Braid the raven hair" is sung as a duet.

Veteran Simon Masterton-Smith (pictured left) plays the Mikado as a big man light on his feet, and throwaway in his punishments; the compulsory choruses to his big number are amusing. And Strobel, looking every inch the part as the dragon betrothed, manages to make her brief moment of pathos in the Act I finale - supported by backing group, good idea - so touching that I wonder why her Act II soliloquy got axed, the only casualty apart from that ladies' chorus. From the first, pianola-precise pentatonics of the Eaton-Young Piano Duo, we know the pace is in safe musical hands, and you can almost hear Sullivan's ingenious orchestration in some of their subtler touches. If Gregor Donnelly's designs were only allowed - budgeted? - to go beyond two screens and a selection of ungainly red boxes, and to find a bit more unity in the costumes (though red and black almost bind things together), the production might create a stronger world of its own. But the fact that the cast does all the work without props or clunking gags speaks for itself. The fine ensemble is certainly enough to send you out beaming from this great Savoy masterpiece.

• The Mikado at the King's Head Theatre until 29 November