I remember the drop-dead-gorgeous teriyaki of tuna belly with yuzu. I recall an interesting blancmange-like walnut tofu with miso. There was a glass or two of a pleasing riesling along the way and sparkling mineral water in a fancy bottle. But what really stayed with me from my dinner at the Japanese restaurant Umu in Mayfair, London, earlier this year was the bill: £292 for two. And we weren't even trying very hard. Umu specialises in multi-course Kaiseki menus, the cheapest of which is £90 a head. We had the second cheapest with the wine pairings at £120 each. They top out at £250 a head. Excluding service.

I was not surprised, therefore, to see Umu fingered last week by the latest edition of the Harden's restaurant guide, as one of four places in the capital where a standard dinner now costs a minimum of £100 a head. Along with Sketch, Le Gavroche, and Blake's, Umu was picked out as a symbol of a rare boom in the London restaurant world. Terrorists may be trying to kill us. House prices may be on the slide and inflation on the up, but there are still fat-walleted city boys out there willing to drop a ton or more on a fish supper.

This was hardly news to me. In the six years that I have been this newspaper's restaurant critic, I have seen prices at the top end rising faster than a pensioner on Viagra. Indeed, it is also hard to avoid three figures a head at Restaurant Gordon Ramsay in Chelsea, the Greenhouse in Mayfair, Petrus in Kensington, and both the Fat Duck and the Waterside Inn at Bray in Berkshire.

The rest of the media, however, responded with customary outrage. One newspaper described Harden's as having 'named and shamed' the ton-up club.

Let's be clear here: the food at Umu is not worth £100 a head. At that price the sushi should have been the best I have ever eaten and it wasn't. Damn it, at that price the sushi should have given me a joke and a song. And anybody who goes, unmedicated, to Anouska Hempel's Blake's hotel to spend £25 on a starter of salt and peppered soft-shell crabs when they can be found at twice the quality and a quarter of the price in Chinatown, deserves everything that's coming to them.

But that does not mean there is something intrinsically wrong with a meal costing £100 a head or more, and it is a peculiarly British response to assume that there might be. We still cleave to the notion that because we need food to survive, hyper-expensive restaurant experiences are somehow amoral.

That attitude was summed up by one commentator who felt moved to point out that 'half the world is starving'. If that's the standard we are using then it shouldn't be applied just to the big ticket places, but to all restaurants. It should also be applied to the contents of your fridge. Stop wasting your money on those Tesco Finest lemon curd yoghurts. For godsake! Half the world is starving! Equally, going to watch a movie, or buying a book or watching TV is amoral because it is not necessary to our survival.

Once we clear that argument out of the way we are left with the simpler question of whether it is ever possible for a meal to be worth a three-figure sum. If you stop regarding it as simply eating out - as an alternative to staying home and grilling the steak for yourself - and put it firmly in the category of memorable experiences, then the answer has to be a resounding yes. I always argue it this way. If you are a football fan how much would you be willing to pay to have the best seat in the stadium to see your team play in the FA Cup final? If you are an opera lover, how much would you be willing to pay for a box at Covent Garden to see Placido Domingo sing? Suddenly £100 a pop seems cheap - and those experiences won't even sate your hunger.

What counts here are priorities. I dislike football, and I would rather nail gun my own tongue to the floor than be forced to sit through an opera. But I adore restaurants, though not, it should be said, indiscriminately. As I say we are trading in the stuff of memories here, and it has to be FA Cup or Domingo standard to justify the price. There has to be a chef of genius at work.

Umu did not justify the price. But, for me, a meal at Le Gavroche, a temple to high French classicism, where dinner comes in just shy of £300 for two, has on the very rare occasions I have afforded it, always justified the price. Likewise, Heston Blumenthal's 16-course tasting menu at the Fat Duck in Bray - with the modernist fancies of sardine on toast ice cream, snail porridge, salmon with liquorice and carrot toffee to finish - is worth every penny of the £97.50 it costs (before wine, water and service). I am fortunate to have surplus income and this is how, once a year, I like to spend it: in restaurants. You may not want to spend yours that way, but it doesn't mean I am wrong to do so with mine.

The question is what am I getting for this? Is it just about the food? Well, yes and no. At the top end, a restaurant experience should be about the moment. It should be theatre, both high drama and low comedy. The setting should be unique. The service should be fantastic, at its best a collaboration between staff and diner, and the wines should be up to snuff too. But the food must deliver. Without that, it's like going to the opera, marvelling at the sets, adoring the lush sound of the orchestra but then discovering that the diva can't carry a tune.

Happily we have a few places in this country which do justify their prices, though it is nothing compared to what's on offer in France. There £97.50 looks anaemic. At the Auberge de L'ill in Alsace there is a single starter, a whole truffle cooked in pastry, which costs a nose-bleeding €135, which is a shade over £97 by itself. At the restaurant of Alain Ducasse in Monaco there is a dish of glazed Breton lobster with caviar which costs €154 (£110). The tasting menu at Marc Veyrat's restaurant in the Alps is €380 (£275). French commentators occasionally question the economics of these businesses, but it is a very rare voice that doubts the principle.

This is, of course, simply the product of differences in gastronomic culture. In Britain an interest in restaurants is something that has permeated down from the moneyed classes, in a gentle seepage that can be traced back to the aristocracy's Grand Tours in the 18th and 19th centuries.

In France, it has always been from the bottom up, from the notion of le Terroir to which the French adhere, with the grandest restaurants being merely the pinnacle of a gastronomic pyramid. I remember Albert Roux of Le Gavroche once telling me: 'In Paris every taxi driver will know the price of black truffles and will be saving up to go and eat them.' In London every taxi driver is more likely to know the price of a box of Black Magic.

Meanwhile people like me will continue to save up. I will continue to seek out the grandest of restaurants and the grandest of dishes. I will luxuriate in the moment. And when the three-figure bills come I will drop the plastic without flinching.

Global gastronomy

Masa, New York
Signature dish: Foie gras shabu shabu
£195 per head average

Umu, London
Signature dish: Sushi and sake-flavoured soup with sea bream.
£90-250 per head for a multi-course set menu

Marc Veyrat, Annecy, France
Signature dish: Exploded bass, a brush of white chocolate, sugarless lemongrass, syrup from Madagascar
£255 per head for 17-course Symphony menu

Alain Ducasse au Plaza Athenee, Paris
Signature dish: Crêpes d'automne en fine pâté croustillante
£205 per head for set menu

L'osier, Tokyo
Signature dish: Foie gras de canard
£85 per head average