Bardo St James’s Restaurant – a name which reads like a map – is a vast new Italian restaurant in one of the pale imperial palaces off Trafalgar Square, near Pall Mall and The Phantom of the Opera, which goes on because snobbery and sado-masochism are among the many things that never die. You might think Bardo (I am not typing all that again) would fold down and fold up in a night, like Cinderella’s coach – it feels flimsy – but these restaurant palaces by Pall Mall are surprisingly robust. The last time I ate in this district it was at the Imperial Treasure, a gloomy and magnificent Chinese restaurant where a performative duck was £100. I thought it wouldn’t last – it was just us, the waiting staff and the duck – but it did.

The entrance to Bardo is a lift to the basement, and beyond the lift is a closed red velvet curtain, which you have to fight with to gain entry. I like this. Beyond that are charming women – I haven’t met a rude waiter in London for many years – and the long, low salon of all Sally Bowles’s dreams. I am sorry to bang on about Weimar, but that is where restaurant design is. I didn’t know it cared so much about the fragility of liberal democracy, but cushions can say a lot if you listen to them. So can chairs, and righteously. The chairs in the anteroom to the loo are by House of Hackney, and I covet them, and if I thought I could have got away with it, I would have stolen one.

Bardo is all beautiful: red velvet chairs, white tablecloths, a greenish Art Deco bar, a bandstand, a piano, the dimmest of lights. Money and faint depravity circulate like air. At dusk, though – I eat early, primly – it is almost empty, which is how I like a nightclub that is also, incidentally, an Italian restaurant: full of expectation. (Its owner, Luca Maggiora, began in nightclubs, and you can tell.) It is just my friend and I, and a man who doesn’t raise his eyes from his iPhone to order. When Sally Bowles herself appears – there is a singer, and she sings her blues – he does raise his eyes, though momentarily. Perhaps he does not understand loss.

The food is far finer than it needs to be, though these are early days: the chef, Graziano Bonacina, was recruited from the Bulgari in Kensington, and he knows his trade. It is delicate Italian food, but it never crosses into whimsy or narcissism: it is loved. We take a vast plate of prosciutto e melone, which is as good as it gets; a lovely and delicate chicken broth, which is surprising, because grandma doesn’t live here any more; a doughty and rich penne arrabbiata; insalata di pomodori with dense and sticky garlic; a tiramisu, the finest trifle.

As we leave, we pass a special room: a table set for two in a minute and quite sinister wine cellar. This whole restaurant is a cellar, so this is a cellar within a cellar, and the wine closes in.

I think Bardo is the restaurant Park Row, the ludicrous Batman-themed restaurant in Soho, wants to be: it’s easier to be an authentic underworld if you don’t call it by that name. Above all, it feels ephemeral, as if I could return tomorrow and find it all gone, and replaced by an office or a car park or, more likely, nothing, not even a memory. If I am paraphrasing American Psycho, it wasn’t conscious, at least initially. I would say the Spectator reader would like Bardo, but go early, as I did, before your glass coach turns to ash.