Matthew Bourne's Swan Lake, Sadler's Wells

For a choreographer the moment your work becomes a classic is when the audience tells you that you’re casting it wrong. I’ve seen Matthew Bourne’s Swan Lake more than a dozen times for professional reasons since it first took off from Sadler’s Wells nearly 15 years ago, and it’s not Adam Cooper’s blinding image all those years ago that’s telling me the press night cast last night wasn’t delivering what the work is worth.

I don't say this is Ibsen with wings, but the potency of Bourne’s rewrite of Swan Lake lies in the true emotional intensity under the topical comedy and fashions, the way he understands in theatre terms the fatal potential of loneliness, and equally the fatal potential of trying to cross from one world to another and belonging in neither. That of course was Tchaikovsky’s own situation too, and it’s what makes that music so heartrending.

Over 15 years any work as topical as this in its jokes, references and sexual atmosphere must be refreshed, and Bourne says he has tightened up the drama and choreography for this revival - but last night it seemed to me that one of the story’s essential sparkplugs, the class system, had gone missing. Presumably Bourne wanted a change for today’s audiences, but I think it’s a mistake.

The problem, I've noticed, is rarely with the Swan, who just needs to be suitably awesome and eyecatchingly sexy whether in feathers or leathers. Richard Winsor was both in spades (he is the Michael Clark lookalike who was Bourne’s Dorian Gray last year).

No, it’s the Prince whose dilemma we’re living through. That role can take a lot of variety in age, sexuality, likeness or not to Prince Charles - what matters is that the character is fatally awkward, hates himself and his sense of separateness, and is instantly vulnerable to the gorgeous strength of the lead Swan. A key factor in this vulnerability is that he is a social class apart, who can't even go to the toilet on his own, but Christopher Marney conveyed nothing of that in his body language,  too common and vigorous a mover by half to be the cloistered, pent-up prince.

Agreed, the changes in the world since 1995 have altered our eyes on Bourne’s jokes about a Queen with a repressed son who gets a blowzy girlfriend. We now have a Queen with a son who wasn’t too repressed to get a wife to give him heirs while he kept a mistress for fun, and then married the mistress on the wife’s demise. So the joke needs now to be subtly different, harsher, more about the mother-son dependency (one of the many echoes of Kenneth MacMillan’s traumatic ballet masterpiece Mayerling that we nerds enjoy spotting in this piece).

Again, though, some over-coarse playing reduced this possibility, from both Marney and Nina Goldman as the Queen (I shouldn’t remind you about Scott Ambler and Lynn Seymour a few years back, but I can’t help it - they're there, scarring the memory). The toy Corgi is still funny, but if the Royals aren’t played as a brittle class apart from the rest of us, we can’t despise or pity them as much as we would like to.

The cheesy send-ups of TV and movie icons are still fresh enough to giggle at in the nightclub scene and the red carpet parade of foreign princesses at the palace ball. The cod-gala performance with Royal Box accidents is a gem of OTT ballet costuming by Lez Brotherston, whose brilliant designs have stood up wonderfully, particularly that magnificent Prince’s bed, full of secrets. The bed is the centrepiece for the haunting final scene, enduring as one of the major images created in modern British theatre, when the Prince lies raving while Swans slide out from under his bed like rats, ready for his blood.

This time round the Swans’ dances outstayed their welcome - there is at least one number too many - but that was I think because Bourne’s male dancers now are a much more motley lot, dancing with rough contemporary enthusiasm and less of the precision and finesse that being led by Adam Cooper for several years encouraged in past packs. The choreographic material may not be the richest in the world, but its images of pecking, walloping wings, a non-human heartbeat, are right, and they need to be precisely understood and delivered. Also, sorry to say, some of the Swans' physiques are porkier than looks fetching in the famous feather breeches.

One thing that pulled no punches was the little orchestra led by the golden-toned violin of Abigail Young, making a sound twice its size. So if last night’s show fell a little flat, it’s nothing that can’t be fixed.

Matthew Bourne's Swan Lake online booking performances until 24 January at Sadler's Wells, followed by a UK tour. New Adventures' website

Check out what's on at Sadler's Wells this season