Property: Splashing out: the shock of the blue: A ruined chapel near Bath, London mews houses - people are fitting pools in the most unlikely places. Caroline McGhie asks why owners take the plunge

GUESTS arriving at Cathy de Lotbiniere's new house - an elegant 19th-century villa near Tunbridge Wells, Kent, designed by Decimus Burton - naturally admire the architecture, the garden, the view. But it is the swimming pool, not something Cathy particularly wanted from a house, that has become the focus of attention.

It lies like a block of blue sky across the lawn, a 20th-century

arrival dominating what were described on the original site-plan as 'pleasure gardens', a magnet for children and adults alike. A feeling of wellbeing somehow seeps out of it, and guests settle dreamily into deck chairs with their drinks to watch the action in the water.

'We didn't want the pool at all,' Cathy says. 'We thought it took up too much of the garden and we weren't sure how safe it was for the children. But now we are here we absolutely love it, and the children are never out of the water.' She has passed through a gruelling beginner's course in the art of swimming- pool maintenance. 'When we arrived it looked dreadful. It was dark green and slimy, full of newts and frogs, and there were lots of leaves and masses of pine needles. I just didn't know where to begin.'

There followed three visits from the swimming-pool maintenance team, all during torrential rainstorms, to tackle first the filter, then the pump. 'They had to shock the water by putting what they called shock chlorine in it, and several cans of purple stuff which made it go all milky. They explained to me how to backwash the filter. But this turned into a hedgehog, bristling with pine needles, soon after they left. So then I opened it up and lost the water pressure. It went gurgling away and I couldn't stop it.'

Back came the maintenance team. After much removing of gunge and slurping of water, they overhauled the pump. Cathy has since tackled the 'creepy-crawly' - a snake-like gadget that moves across the bottom and vacuums up the silt - and she has got her kit together to test the water every three days to make sure the chlorine and pH levels are right. She has also learnt that in the winter she will have to drain the pipes and put a plastic lemonade bottle, weighted with stones, into some part of the pool's mechanical anatomy to act as a crumple zone when it freezes.

Cathy's major triumph so far is putting the foot from a pair of tights over the skimmer valve to stop those pine needles from doing another hedgehog. 'I've run out of tights now, and I'm a bit worried about them being sucked away . . .' But . . . it is lovely on a hot day, or even on a cool one, since the children don't seem to mind turning blue. Cathy's husband, Nick, who is grappling with his own induction course in commuting, swims naked in it every morning before he catches the British Rail snail. And, for the moment, the pool gives him an added incentive to get home in the evening for a reflective gin and tonic.

The Lotbinieres have joined a growing breed of pool people. There are now at least 150,000 private pools in England, approximately one for every 40 houses. Other Europeans, predictably, lead the way: one in 10 Belgian homeowners has

a pool, one in 17 French, and one in 35 German. But in England the weather rarely provides enough warmth for constant use even during the summer, and a private pool represents pleasure without profit.

According to Savills estate agents, sellers of houses to the very rich, you can realistically expect an outdoor heated swimming pool to cost from pounds 25,000 to install, but you cannot expect it to add more than pounds 20,000 to the value of the house. An indoor swimming pool will cost pounds 75,000 upwards and is unlikely to add more than pounds 50,000 in value. A hard tennis court makes a much sounder investment. It costs about pounds 15,000 to lay, is very cheap to maintain, and you get your money back when you come to sell the property.

There are exceptions to the pool rule, however. One of the most spectacular of these, currently for sale, is in an extraordinary setting at Bradford-on-Avon, near Bath. It lies within the walls of a ruined, roofless, stone chapel which provides such an astounding backdrop that it features in local guidebooks. Miles Kington once flew over it in a balloon and mentioned it in the Times.

The property belongs to Mariana Shaw, who fell in love with a picture of it in an estate agent's window. Recently married, she is now selling the four-bedroom house and pool through Savills with a price guide of pounds 235,000 - boosted by the romance factor. The previous owner had bought the house with very little land, then snapped up the old Wesleyan chapel on the slope below and created the pool and Italianate terraced gardens leading down to it.

'It is amazing,' Mariana says. 'One of the ladies who cleans actually got married in the chapel before it fell into disuse in the Sixties.' The previous owner used to hire it out through a film-location agency but for Mariana, a chartered accountant, it has provided the setting only

for memorable weekend parties. 'It is floodlit from underneath, so the water is reflected on the walls of the chapel. I just love entertaining, so it was a lovely vehicle for that. I do all the cooking myself and I remember once doing curry for 100 round the pool,' she says. 'You become a very popular person with a pool, and dinner parties invariably all end up in the pool. Men particularly enjoy it - they like doing all the hoovering and they become very infantile when they are in it.'

She is aware of the newt nightmare that Cathy de Lotbiniere encountered. 'If you let it go, a beautiful, clear pool becomes a primeval swamp overnight, especially if it is summer - then the algae grow incredibly fast.' She says that it costs very little to keep the

pool heated: bills for the house and pool in the summer quarter came to about pounds 200. 'You have to fire it up, which takes about a week. Then you make a rule that, no matter how pissed you are or how late it is, you cover it up. Then all the heat stays in.'

Some people manage to take the business of pleasure even more seriously. At Green Acres, a ranch-style country house in Warwickshire, there are not only a grass tennis court and a snooker room (and remote-controlled curtains throughout) but also a leisure complex with a pool, a games room for table tennis and fitness machines, a changing room with a shower and a built-in bar. This, too, is for sale through Savills, at pounds 375,000.

The Green Acres pool has a jet- stream wave-making machine that can project such a current through the water that you can swim against it for hours and never reach the other side. 'It means you don't have to bother with turning round every time you reach the end,' says the owner, Tim Lambert. Alternatively, the jet can turn itself into a jacuzzi that massages you while you hold on to the wall straps. How big have his parties been? 'Are you counting bottles or people?' he says, in the way that pool people do.

You don't have to be enormously rich to join the pool set. According to Paul Gosling, director of Signet Pools, inflatable pools start at around pounds 1,500 and all-in-one moulded glass-fibre ones around pounds 3,000. An above-ground galvanised steel pool with a 15ft diameter can be bought for as little as pounds 300, rising to pounds 5,000 for one 15ft by 30ft.

'They have rather basic cleaning and filtration equipment, but in Canada and Australia people love them,' he says. 'They build wooden decking around them and they last a good 10 to 15 years. But they have a different attitude towards their gardens. They have a back yard to do things in. We have gardens which are supposed to look pretty.'

To dig a pool and line it, costs from around pounds 10,000, and the Signet concrete-shell pool, lined with mosaic, starts at pounds 22,000 and rises to pounds 100,000. The installation is horribly messy and some of the cost depends on ease of access to the site. In central London, pools often have to be hand-dug. Once you reach the suburbs, the price drops because it is usually easier to get

mechanical diggers in.

The drawback is that the landscaping, paving and lighting can cost as much as the pool again. 'We did one job where the pool cost pounds 26,000 and the natural stone paving and log cabin changing rooms and landscaping came to pounds 32,000,' Mr Gosling says. 'An indoor pool will cost three times the amount of an outdoor one because a lot of people go for total environmental control. The air is sucked out and reintroduced along the glazing so that it doesn't mist up.'

The Swimming Pool and Allied Trades Association is at Spata House, Junction Road, Andover, Hampshire SP10 3QT (0264 356210). Signet Pools is at Station House, Tadworth, Surrey KT20 5SP (0737 814440).

(Photograph omitted)