Rub-a-dub-dub, the guests are in the tub

He had used his new swimming pool eight times the previous year, which worked out at £3,500 a dip

Some years ago, I can't remember why, I flew anti-clockwise in a helicopter between London's four airports starting at Luton and finishing at Heathrow with a break at Gatwick for a swim at the airport hotel. It must have been a press trip organised by the British Airports Authority to show off some important new facility – a theme park next to Tie Rack at Stansted possibly, to entertain Ryan Air passengers waiting for their delayed flights.

All I remember is looking down at the Home Counties and marvelling at the number of swimming pools we were flying over, so many that we played a modified version of that game families play on long car journeys. One point for a straight rectangular pool, more if they were fancy, kidney shaped, heart shaped or those long, thin ruler jobs that exercise freaks install specifically for practising lengths.

I am now in a position to reveal that Surrey favours kidney-shaped swimming pools. Buckinghamshire and Hertfordshire, especially around Potters Bar and Hatfield, go in for the classical look with Greek temples and roman pillars fringing their spa areas. Essex is the home of the heart-shaped pool, invariably landscaped into a Caribbean setting featuring a lot of thatch and decking.

Bearing in mind the brevity of the British summer, it seems extraordinary to me that so many people are prepared to spend so much on immersing themselves in tepid water for a few minutes. I once sat next to a man at dinner who told me gloomily that he had used his new swimming pool eight times the previous year, which worked out at £3,500 a dip. On the other hand if you've read any of Elaine Morgan's books, the reason for our preoccupation with water becomes clear. I think it was in The Descent of Woman that she first aired her aquatic ape theory, which basically rubbishes Darwin and claims that humans evolved not from apes in trees but from fish in the sea.

Her theory is based on certain incontrovertible facts – unlike mammals but like fish we are hairless, blubbery, walk on two legs like penguins and cry like crocodiles. Condensing it like that is unfair to Miss Morgan, whose anthropological credentials are impeccable, but she had more space. Besides, I want to tell you about an enterprising young man I met last week who has just thrown up a successful career in television to start the first portable hot tub company in Britain.

As the proud owner of a permanent hot tub I was impressed but sceptical when Yomi told me breezily that he hires them out for weekends and parties. When our cedar wood tub arrived two summers ago on the back of a lorry I had to bribe five Italian waiters from the local pizzeria to carry it to a suitably bucolic spot. It weighs a ton, takes four hours to fill and 24 hours to heat, which doesn't leave much slack for a weekend hire.

Yomi, who has to be the most laid-back young man in London, smiled and said that his tubs are made of the same tough, synthetic material they use for inflatable boats and his weekends start on Thursday. He put one in the middle of Epping Forest recently for a four-day celebration of counterculture, but he can put them anywhere, meadows, barns, nightclubs, rooftops, wherever you want. "I can facilitate any dream you have," said Yomi. I particularly warmed to his Garden of Eden theme where the marquee containing the hot tub is filled with rose petals four inches deep, serpents and apples optional.

Give me a hot tub in preference to a swimming pool any day, especially in winter where there's so much steam coming out of it you can scarcely see the frost on the grass. Nothing is as relaxing. If you sit directly in front of the water jets it's like being massaged by a sumo wrestler.

Long ago, when I did such things, I went to one of Andrew Lloyd Webber's midsummer parties at his Berkshire pile. He had a huge hot tub on the terrace and after dinner the less sober of us peeled off our clothes and jumped in.

"Oh please, please, could you not take your champagne in with you, it's so dangerous," pleaded his wife, more significantly soon to be his ex-wife, in obvious distress by the side. "For God's sake, Sarah, relax," came her husband's voice from the whirlpool of limbs and bubbles. Poor Sarah. If only she had, she might still be queen of Berkshire hot tubs.