It was The Valkyrie last night. Mounted fit birds who pull corpses. This must be the most concentrated and emotional five-and-a-half hours available in the western canon. I went to the dress rehearsal in the £20 seats with a restricted view, which makes you feel like Spider Pig, but is a blessing because you only have to see half the set.

Why is it that opera design works to a completely different and lower standard than theatre, ballet or Punch and Judy? The sets invariably look like collaborations between a 16-year-old girl who wants to open a nightclub, a Kwik-Fit fitter and a drunk bank manager: hopelessly intellectually insecure and imaginatively verbose. They want to compete with the music and plot, the metaphor and allusion. It is like having an insistent, stupid show-off on stage trying to attract your attention. Sometimes a chair needs to be just a chair and not a symbol of the imminent rise of fascism, or a knowing nod to the fact that Wagner’s father may have had an affair with an upholsterer called Brünhilde.

Behind me stood navvies with pretrendy tattoos, their little fingers just touching in the dark. Wagnerians are the strangest audience in all culture; stranger than darts groupies, more obsessive than Millwall supporters. This being a rehearsal, Covent Garden was mercifully free of corporate-entertainment charabancs and banks’ boring clients. And there were no newly minted plutocrats trying to impress the knickers off chilly sloane totty, in the forlorn hope that they’ll get back to the Inn on the Park and she’ll whisper, “Shag me in the tradesman’s, you appallingly common little oik,” in a voice like a breaking gin bottle.

Frederick's

Why the waiter particularly singled out the fishcakes from the piles of congealing manna on the table, I couldn’t say

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These are the true fans, the aficionados, the ones who bring their own sandwiches and medication, the ones with hip displacements and gaudy warts on their heads. They have the look of people who escaped from Brueghel and once opened a door to see something unspeakable; people who have thought too much and said too little. Tonight, there are an awful lot of self-denying gay men, chaps whose personal closets have the lock on the inside. They sit in the Crush Room, folded into tight grey flannel squares, defending their personal space against pheromones and yearning.

One of the little Vorspiel highlights is to stand in the corridor and enjoy the Wagnerian dash – more a sprightly trudge – to the lavatories as the first bell rings. Everyone knows that this is a pelvic-floor clencher, and most of the audience is of an age where the elastic is a bit frayed. Towards the end of the second act, you can feel the drip, drip, drip of anxiety, the quivering sphincter of doubt. It’s like being on the motorway and having the empty light flash on, except it’s the opposite. They ought to have those wire cages like they do at airports for hand luggage: you’re not allowed on board if your bladder is fuller than this.

I overheard a blissful elderly couple having a hissed and heated argument in front of the ladies’ loos. “I’m not going in there,” she said. “That’s not the one I go in.” “What’s the matter with it?” he asked wearily. “I went in that one for Parsifal,” she replied. “Had to wait for ages. I always go in the gods. I went in the gods for Rheingold and Meistersinger. It’s just in and out there. Down here in the stalls, I don’t know what they do. Getting their money’s worth,” she added with an opaque, heartfelt venom. When you get down to it, an awful lot of opera is about bladder control.

This week’s restaurant is everything that the Ring cycle isn’t: small, mean, flashy, trite, fashionable and with rubbish music. Crescent House is a converted pub in Notting Hill. There is barely a pub that hasn’t been converted up here. This is mecca for converting pubs. There’s a comic song about a pub with no beer. Well, that’s Notting Hill.

On the whole, I’m keen on pubs improving their kitchens. It’s the way of filling in the middle ground of restaurants that are better than takeaway chains and not as expensive as table cloth and five-sorts-of-bread places. What doesn’t work is when they convert a nice old boozer into some sort of Brazilian finger-snapping, snobby greenroom for the socially aspirational and sexually famished.

Crescent House is all born-again conversion and no pub. Downstairs, it was get you, bootie sizzlin’, right here, right now über trendy – so whisperingly need-to-know elitist that they plainly haven’t found anyone smart enough to tell or allow in. Upstairs in the restaurant, there were a couple of silent couples, who looked like the line drawings that architects stick on building plans to add scale, and wallpaper on the ceiling. We could really stop the review just there. Everything you need to know is encompassed by ironic wallpaper on the ceiling.

The cook is one of those chaps whose previous is impressive, expensive and Michelin-hungry. He has brought with him a chichi, finicky, manhandled little menu that’s absurd for a pub, even one that’s converted. I started with a salad that had artichoke hearts and oven-wizened tomatoes. It was yawningly familiar and instantly forgettable. It’s a general, all-purpose starter for people who don’t want to eat.

Next, I had the beef and the Blonde had the duck. They were memorable, solely because they both came with the same overcooked meat reduction, like melted lip gloss. I may be doing the kitchen a disservice here; perhaps they actually had taken hours and hours to diligently make duck gravy taste exactly like beef – or vice versa. Pudding was a cheesecake with a layer of fruity jelly on top. Passion, I suspect. It peeled off in one satisfying strip, like a wine-gum toupee.

The waiter was perky, ingratiating and chummy. He simply underlined a truth about the duck, him and me: we were all in the wrong place at the wrong time. You can eat downstairs all day – or, like all the locals, not. The menu enthusiastically points out that, for them, Sundays are a religion. Do you think we should tell them they’re not the first people to have thought of that?

Crescent House is a hollow triumph of fleeting style over plagiarised content. If it’s still here in a year, I’ll eat the chef’s hat. Which is preferable to his à la carte.

41 Tavistock Crescent, W11; 020 7727 9250 Dinner, Tue-Sat, 6.30pm-10.30pm

5 stars: Pub crawl; 4 stars: Pub quiz; 3 stars: Pub landlord; 2 stars: Pub grub; 1 star: Pub with no beer

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