But I suppose if you were to argue that central London begins and ends within a 200m radius of Trafalgar Square, you'd have to concede their point, because by that token Thai Square is the only Thai restaurant in central London. Which must also make it indisputably the most soul-less, mediocre and tourist-infested Thai restaurant in central London. Not that they're ever going to tell you that on their leaflets.
Which is a shame because I was really looking forward to my evening there. I love Thai food - it's like having an Indian and a Chinese all in one go - but I hardly ever get to eat it because most of the decent restaurants seem to be on the other side of town from me in west London and, relative to other "ethnic" food, it's a bit too expensive. And though Thai Square's pounds 8.95 three-course set lunch (plus free glass of wine) might well represent a considerable bargain, it's pounds 25-a-head upwards evening menu most certainly doesn't.
The restaurant's biggest drawback is its location (in the former Norwegian Embassy) just off Trafalgar Square. While this makes it highly convenient for pigeon-fanciers and new lottery winners (Camelot's offices are right next door), it also inevitably means that the place is infested with tourists, out-of-towners and other flotsam and jetsam.
The result is a totally atmosphere-free zone. Unless, perhaps, you count the ersatz atmosphere provided by the lavish Thai decor (gold pillars, stone idols, mini-fountains, elaborately carved wooden thingumajigs, etc) and the occasional outbreaks of traditional Thai music and traditional Thai dancing. But all this serves to do is make you feel as if you're sitting, jetlagged and bewildered, in the lobby of the Bangkok Hilton. And even when the place is busy and noisy - as it was on the Tuesday night I visited - there's a depressing lack of buzz.
All this might yet be forgiveable if they knew how to make a proper Singapore Sling (they don't); if the service was first-rate (it's well-intentioned but haphazard and often slow); or if the food was remotely memorable (which it ain't). As a benchmark, we ordered a classic - Thai green curry with chicken - and, though it stood up reasonably well against all the zillion and one other green curries we'd eaten over the years, it didn't exactly sing with culinary genius. It also happened to be the best of all the dishes we ate - which doesn't say much for the rest.
For some reason, I find ordering from Thai menus deeply traumatic and I always wish that the waiter would decide for me. Maybe, if we'd let him, he would have chosen something less boring than the promising-sounding Payakpoopee - aka "Weeping Tiger". Though it was perfectly OK - strips of good, well marinated if slightly overdone steak, served on a metal platter - it didn't compete with the sizzling Szechuan steak I get at my local Chinese or the Sha King beef at my local Vietnamese. And at pounds 10.95, it should have done.
Anyway, the one dish we did let the waiter choose turned out to be the feeblest of the bunch. This was the Talay Tong - fried mixed seafood flavoured with lemongrass, chillies, garlic and basil leaves - and though it looked pretty regal and sumptuous, the constituent fishy bits (tired prawns and squid, flaccid crab claws, mussels which we dared not eat) were pretty manky.
As for the rest, the coconut rice was fine, the sticky rice congealed almost to the consistency of gnocchi (the result of hanging around too long in the kitchens, I'd guess), the prawn spring rolls crisp and OK- tasting, and the Kai Ho Bai Teoy (chicken in spinach leaves) like a slightly upmarket version of chicken nuggets. Or, according to Robert the royalty correspondent, "just like fish 'n' chip shop chips".
Robert, incidentally, has just started doing restaurant reviews for The Spectator and was eager to discuss technique. Once he's eaten, he actually takes the trouble to interview the chef and he also makes copious notes throughout dinner, disguising the fact that he's a critic by pretending to be interviewing his dining companion. "And tell me about your next TV series," he says loudly, whenever a suspicious waiter draws near. He was surprised to hear of my own lack of note-taking, but then my theory is that it's a critic's job to have exactly the same experience as an ordinary punter. Also, I'm lazy.
"So you'll be giving this place the thumbs down, then?" he said, at the end of dinner. "Yep," I said. "Pretty much." Thai Square isn't good and it isn't bad. It's just OK. Exactly what most of its tourist clientele would expect of London cuisine, I imagine.
Norway House, 21/24 Cockspur Street, London SW1, 0171 839 4000. Open Mon-Sat noon-1am, Sun noon-11.30pm. Three-course dinner about pounds 25. Credit cards accepted, except Diners
WHAT'S ON THE WINE LIST
Richard Ehrlich's selection
Matching Thai food with wine is, roughly speaking, impossible and a waste of time. The Thai Square beverage manager seems to acknowledge this by making just a nominal attempt at building a wine list. But you can drink well with these three choices, or with a beer. Don't laugh at item two; it's the best of all.
Bellefontaine Terret-Sauvignon 1998, pounds 9.95
This is a property of no great distinction but the grape, with its exotic tang, could stand up well to the strong contrasts of flavour in Thai cooking
Makhong, pounds 3.25
A Thai spirit distilled from rice. People in restaurants in Thailand drink a bottle, heavily diluted, throughout the meal. Believe me, they know what they're doing
Alsace Gewurztraminer, Domaines Schlumberger 1997, pounds 26.25
Best grape for Asian food; good producer; price that won't frighten the bank manager. What more do you need?