See the words 'Cleese' and 'farce' side by side and I know what you'll be thinking. Is Bang Bang the 13th Fawlty Towers? I wish I could say it is, but that'd be straight outta la la land.

There are problems at every turn with this rare sighting of Feydeau's Monsieur chasse!. John Cleese's adaptation feels like a work in progress, its cogs so freshly tooled they don't yet mesh. The dialogue is over-larded with exposition and low-level filler; and yet such are the great comedian's talents that it's only a few scalpel strokes from being a decent comedy.

Bang Bang's comic trappings are tried and tested but they're rendered with a curious detachment that earned only a moderate response from the first-night audience. Laughs came from the lips, not the belly. The hypocrisies of the adulterous Monsieur Duchotel and his equally extra-curricular wife Leontine have all the requisite hubris, humiliation and trouser-dropping, but the pilot light is out so it never heats up.

Nicky Henson, who helms the show, is a farceur of long standing. As the original Gary Lejeune in Noises Off he had me falling out of my seat, and he did the same to millions more as the bling-and-leather-clad lothario in Fawlty Towers. Nowadays he directs more than he acts and, sadly, the result here is worlds away from those early triumphs. Henson cannot take all the blame, though. On top of all the script issues Colchester's Mercury Theatre has gifted him an uneven cast, and in the second half—up to and including a chaotic curtain call—telltale signs of rushed rehearsal mar the flow. He could have done with another week.

There are happy incidental moments—three thumps à la française to preface each act; an entertaining transformation when designer David Shields's sumptuous Belle Époque drawing room becomes a bordello's bedchamber—but little bliss. A gag about the maid's French accent hits the spot (Jess Murphy in a bright performance), as does a knowing nod from a man being bundled into a wardrobe ("that's a bit corny isn't it?"). One of many meta moments, that. Everything from conspiratorial glances through the fourth wall to full-on audience address.

The role of Duchatel seems to be tailor-made for Cleese himself to play, for it has absurdity, punctured dignity and manic potential in spades. Alas, it doesn't suit Oliver Cotton in the slightest. The lead in a French farce needs a mobile face, something with which this distinguished actor is not blessed, and an instinct for timing that eludes him. During the philanderer's climactic scenes of obfuscation it was hard to tell whether he was blustering through his lies or his lines.

There's solid work from Peter Bourke as the cuckolded Cassagne, a Manuel figure during his brief appearances, and from Robert Neumark Jones as Gontran, the play's hyperactive juvenile interest who could have stepped straight out of Half a Sixpence.

As Leontine, the splendid Caroline Langrishe energises her shared scenes with Cotton, dallies amusingly with Richard Earl's vainglorious Dr Moricet (very good) and does everything in her power to keep the show afloat. Yet even she can't prevent Act Three from beaching on the shore. When Moricet confides to the audience "I don't understand a single thing", be prepared to nod along - or off.

Bang Bang runs at the Mercury Theatre, Colchester until 11 March.