USP Set in the basement of the Mandarin Oriental, an opulent hotel on the edge of Hyde Park, this spa is the epitome of restrained style. Voices are hushed and the spa is almost empty - probably due to the high prices and the hotel's attempts to keep it exclusive. Black-clad therapists discreetly move through the dark granite rooms, showing the elite few where to find the showers, amethyst crystal steam room or the bottled water flown in from Fiji. Tea-lights and fleshy green orchids are the only decoration, this is a serious spa for those with serious amounts of cash.

QUALITY OF EXPERIENCE The treatment rooms are spacious and after a preliminary body scrub I was able to shower in the room and then get back on to the heated couch. Here I was massaged with hot stones by a petite Irish girl, who, frankly, looked far too puny to give a good massage. However, it was one of the best massages of my life - and I've had a few. It was zombifying and the only thing that kept me conscious was the occasional sound of my own snorts as I started to drift off to sleep. I was massaged with a beautifully musky smelling aromatherapy oil which my therapist recommended I leave on for the rest of the day, to allow my parched skin to drink it in. This I did and my skin definitely felt better for it.

AMBIENCE Very subdued. The Zen-inspired surroundings certainly lent a calmness to the experience. With only one or two people using the communal spa area at one time, I could relax totally without worrying about sharing my space. The spa has a great wet area and you start your "journey" in an amethyst crystal steam room. Then a dip in the vitality pool where you follow the hydrotherapy jets around for 20 minutes as they work on different parts of your body. There is a sanorium which is cooler than a sauna, and less drying, so easier to breathe in it; and various showers. The only (very small) gripe was that I couldn't figure out where to put my towel while I was indulging in all these things, so I put it on the floor and it got sodden. Ah! The trials and tribulations of a spa journalist.

IN CROWD Madonna, Jodie Kidd, Michael Caine and Ruby Wax have been spotted. Whatever you do, don't come here with a hen party. This is a place for some solitary me-time, and most people come alone. I only saw two other people there; a young American woman, and an older European woman who had few body issues and strolled around naked. At an international spa like this it is very likely that the other spa GOers are foreign which invites all sorts of fun and games. In most other countries - including the US - people go naked in spas, so if she's got a swimming costume on, she's probably English. This obviously only goes for single sex spas like at the Mandarin, where the men and women have separate spas. If you are somewhere which has both naked men and women, you've taken a wrong turning and found a a naturist camp rather than a spa.

FOOD There is only a delicious herbal teas made from combinations of rosehips, nettles, elderflower, ginger, ginseng, dandelion served in the spa. However The Park restaurant, in the hotel, serves healthy light lunches. Tom yam goong, a spicy Thai soup with Tiger prawns, lemongrass, straw mushrooms and coriander and sorbet and blood orange sorbet is a typical menu suggestion.

WALLET WATCH Aha! Here's the catch. I'm afraid a blissful spa experience doesn't come cheap. You have to spend a minimum of one hour fifty minutes at the spa, and the cheapest treatment of that length is £190 (chakra balancing with hot stones). But for that you get use of the "heat and water oasis", which they recommend spending at least 45 mins in. Although they say they do waxing and tinting "on request", it really isn't that sort of place. It's much more about having a day of luxury and relaxation - forget about any beauty-related pain.

NEED TO KNOW If you're not staying at the hotel, in order to use the spa you should book treatments which last a minimum of two hours. If you are staying at the hotel you can book treatments which only last an hour. If you only want to use the water facilities, you must pay an additional £25 or use them between 7am-9am. Mandarin Oriental 66 Knightsbridge, London (020 7838 9888; www.mandarinoriental.com)

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