Eating habits in the US leave no room for the middle ground. Americans either eat only lettuce or only hamburgers. This is because Americans are forced to choose, at a relatively early age, whether they want to be anorexically thin, so that they can go to Hollywood and become movie stars, or hog-wateringly fat, so that they can go on Jerry Springer and declare how happy they are with their size.

In this way, Americans are like their cities: either lean, modern and super-efficient, like New York or Chicago, or gigantic suburban splats like Los Angeles or Roseanne Barr.

It is not impossible, of course, in the Land of Choice, to be both. Renée Zellweger, for example, can get work looking like a hollow-arsed vision of the Apocalypse or by swelling her form into that of a giant cheese. And Raging Bull was recently declared the seventh best film of all time simply because Robert de Niro plays half the film thin, and half the film fat. They love him, in other words, because he got to eat cookies.

And look at Friends, the world’s most successful sitcom. For a couple of series they all looked fine. Then they got rich. And by the end the three girls looked like sunken-cheeked bystanders in an anti-heroin poster by Edvard Munch, while the boys were rolling around like cheeky faces painted on party balloons.

In Britain, we are, still, a little more moderate, and so it is no surprise that sit-down American cuisine has never really taken off in restaurants here. It’s either about diet plans so faddy that the fad is finished by the time you go back for seconds, or so soultastically mommalicious that you drop dead from a massive coronary before you have a chance to get out of the door and tell your friends about it.

So what are we to make of Automat, a self-styled “American Brasserie” just recently opened in, of all places, Mayfair (“I say, Jeeves, if that isn’t as rummy as a bison pie with mint sauce and double extra redskins?”).

To begin with, I have no idea what an Automat is. Indeed, it is very probably the word whose meaning I have not known for the longest time without bothering to look it up. Twenty-six years, to be precise. Because I was nine years old when I stayed up to watch Gentleman Prefer Blondes on BBC Two, thanks to a write-up in the Radio Times which suggested that it might present an opportunity to see Marilyn Monroe’s breasts (and also Jane Russell’s, although those did not interest me, since what is true of gentlemen is true also of nine-year-old boys).

The film was, of course, a terrible disappointment: feeble plot, laughable characterisation, a rank insult to liberated women, and not so much as a glimpse of nipple. And as for the songs, The Jungle Book it most certainly wasn’t: “A kiss may be grand. But it won’t pay the rental on your humble flat. Or help you at the automat…” She didn’t have a washing machine?

And then Automat opens in Dover Street, with clam chowder and soft shell “po boy” and roast turkey on rye, and I have to assume that all along an automat was some sort of automatic restaurant. Silly me.

As for this Automat, it is, in my opinion, absolutely stunning, though by no means automatic. I do not, in general, give a rat’s arse for “restaurant design”, and am generally baffled by the list of names presented as “celebrity restaurant designers”. Nothing turns me off a place more than some gushing, thick-vellummed PR paean to “lush drapes by Neneh Cherry complementing the million-dollar Wilkie Collins redesign and glassware by Felipe Snark”. But at Automat – designed by a New York architect called Carlos Almada – I was positively gasping at how lovely it looked. Worse, I found myself saying “gosh” a lot. Mayfair can do that to a chap.

One walks in off the street into a gleaming, tile-floored, clacky-chaired space which looks wondrously functional in an olde fishe shoppe sort of a way, though it was not being used for diners when I went, and is perhaps used as an overflow.

The next room (with the same mosaic floor continuing through) is deeply wooded and leathered, luminously brown and opulent, gently mirrored and boothed and windowed, all in a Pullmanish way that put me in mind of J. Sheekey, the most effortlessly perfect restaurant interior in London. According to the PR guff, this room “evokes the simple horse-drawn carriage wagon of the late 19th century”, but I must say I wouldn’t want to have to escape in it from a band of hostile Comanche. For I feel it would remain firmly rooted in Dover Street no matter how furiously I waggled the reins and however loudly I screamed “yee-ha!” I went on through into the back, which has a sort of conservatory feel, with a bar and big white tiles and lovely glass doors and an open kitchen – in the restrained but focused mode of Fergus Henderson’s St John, but with nice frosted Thirties lamps and green leather banquettes to make it a little more chi-chi.

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