The Gondoliers, Coliseum, London <!-- none onestar twostar threestar fourstar fivestar -->

It's sink or swim time in Venice

The jokes weren't so much landing as held in a holding pattern for much of English National Opera's first ever staging of Gilbert and Sullivan's The Gondoliers. One was reminded - if, indeed, one needed reminding - that the so-called Savoy Operas are no walk in the park for even the most seasoned professionals.

Of course, ENO still has in its repertoire the most successful of all latter- day Gilbert and Sullivan revivals - Jonathan Miller's brilliant 1930s revamp of The Mikado - but that, quite apart from falsely raising expectations, only serves to remind us that G&S needs an angle, a gimmick, a smart rethink, if it is to come off the page and stage today. Keeping them light, keeping them gay, as a certain Mel Brooks "Producer" once suggested, is a start, but only a start.

Martin Duncan and his designer Ashley Martin-Davis (in their ENO debuts) do gay alright, but they do it without much irony. Martin-Davis's "gay" set is something out of Disneyland's "It's a Small World" - a kiddy-ride evocation of Venetian canals and gondolas. The fluorescently coloured pages of an outsized picture book lie open as a backdrop to the whole unlikely story, and there's a neat visual allusion to the topsy-turvy world we are irresistibly bound to enter.

But then, on come the grown-ups and the set becomes a handicap - as in obstacle course or novelty golf. It's a relief to repair to Barataria - the land where despotism meets equality - in Act II. By then, things have really gone topsy-turvy plotwise, but the show has found its footing performancewise. Gay and camp are at last synonymous.

Part of the problem is that opera singers - as opposed to G&S specialists - just don't know how to play the dialogue. It's a style thing. Much of Act I proved pretty desperate in this respect. I know that social satire has shifted a little in the past 117 years, but that's something you can use - as Miller did so brilliantly in The Mikado. But then, he had the likes of style-master Richard Suart anchoring proceedings. Martin Duncan has Donald Maxwell as a terminally oleaginous Don Alhambra del Bolero, the Grand Inquisitor, and what a relief when he comes on. No wonder he has the entire cast genuflecting. He fills the stage. Attention is paid.

Speaking of which, the casting of Ann Murray as The Duchess of Plaza-Toro certainly got my attention. She and Geoffrey Dolton (splendid as The Duke) drew upon all their collective experience in making "To help unhappy commoners" as offensively un-PC as it could be.

Of course, The Gondoliers is chock-full of numbers as good as that. Gilbert and Sullivan's last great success is among their most sophisticated. Certainly, many would regard it as Sullivan's finest hour, in the sense that the familiar elegance and catchiness now takes some deliciously oblique turns. The Act II quartet, "In a contemplative fashion", is a supreme example of exasperation set in blissful counterpoint to "quiet, calm, deliberation". At such moments, you could easily forget that, half an hour earlier, the show was on its knees.

Perhaps the strangest thing about G&S is the way in which its very particular requirements can so easily diminish first-rate performers. Stephanie Marshall, who has previously impressed in this house, made little or nothing of Tessa's hit number, "When a merry maiden marries"; likewise David Curry (Marco), whose golden-oldie, "Take a pair of sparkling eyes", can, but didn't, stop the show. Sarah Tynan was, as ever, good value as Gianeta, and there was energy and charm from Toby Stafford-Allen (Giuseppe), and promise from ENO Young Singer Rebecca Bottone (Casilda).

But everybody needs to play up and play the game a lot more. Put simply, when in Venice, do as the English do.

In repertory to 27 November, and 2-31 March 2007 (08701 450 200; www.eno.org)