Forty-five Jermyn St lives in the left-hand buttock of Fortnum & Mason (F&M), a shop whose acronym is slightly too close to FGM (female genital mutilation) for this column to be able to relax there for long periods, even though its Diamond Jubilee Tea Salon is excellent. Its name is part of a vogue for naming restaurants after postal addresses, and even street numbers (Richard Caring’s 34 in Mayfair). This is one of the more idiotic, if less gritty, consequences of the London housing crisis: an address — or even a house number — is a brand. The restaurant named after a postcode — and I suggest TW11 0BA in Teddington because there is nothing there — is surely pending. Go for brunch, lick the bricks, adopt a refugee.

45 Jermyn St — ‘old-school glamour meets contemporary London’ — used to be called The Fountain. This restaurant seemed to be composed entirely of flounces and it suited F&M, a peculiarly British palace of dreams that sells heritage relish across the globe. But like an ageing showgirl who married a duke, the Fountain had to be put down. Her flounces carried the tears of boys off to boarding school to lose their childhoods overnight; she smelt of lavender, talcum powder and Harold Macmillan. Did the tiny David Cameron come here, fill his tuck box, re-arrange his tiny face into a tiny smile?

I can’t type the name again because it makes me feel stupid, or like a postman. So I will say it is a bright and spacious brasserie in sage and orange, principally Art Deco, but lying down for a rest. It is a very chic Oslo Court, ripped up and reconvened: the bones are old, the eyeballs — and skin — are new. The customers, despite the rebranding, are still ageing, international (Jews and Arabs, temporarily at peace due to the soothing proximity of food), soft in face and the sort of rich that does not care what it looks like; that is, very rich.

You can redecorate a restaurant, but you cannot redecorate a clientele; that would be rude. In this F&M is powerless; they could fit comfortably into the waiting room at the London Clinic and look no less happy. There is a soft buzz of pleasure in this restaurant, just three days old. F&M was partially founded by a footman to Queen Anne (‘F’) and it has always had the gift of creating ease in hell. (She had a bad life, Anne — seven miscarriages, five stillborn babies, five dead babies.) It is the retail equivalent of the novels of Frances Hodgson Burnett, who argued convincingly that urban Victorian life was not that bad, if you were really very rich. It also invented the Scotch egg.

The prices, in this spirit, are immense. The caviar trolley sells Iranian Beluga for £6.70 a gram, with a minimum spend of £67 (scrambled eggs and baked new potatoes included). Dover sole à la meunière is £36.50 without veg. Glenarm Estate rib steak is £33.50, likewise without veg. I do not think the customers mind the expense; for them it is soothing, if the food holds up, which it does.

We eat a wonderful Welsh rarebit, heaving with salt and fat, and dark sticky salmon with soda bread. The sole is boned at the table, with deft expertise, by a waiter who behaves like a cardiac surgeon fallen to fish. Pudding is less good — the chocolate cake is an alcoholic, and would take us all with it — but otherwise all is fine. The Fountain has died; the world, oblivious, turns.