The original family lived in the two rooms and used the cave for storage or shelter for animals. With little scope for light or ventilation, it’s a difficult space to convert, but would make a brilliant party venue. The agent, Aubrun Thimel is based in Montoire (00 33 5485 0552).To get a feel for troglodyte living, visit La Fosse, near Doue-la-Fontaine (Bernard Foyer’s 19th-century troglo-farm: see text) or the Louresse- Rochemenier commune (an 18th-century rock-cut village, now a museum). To explore the potential of rock-cut construction as contemporary art, visit sculptor Jacques Warminski’s “L’Helice Terristre” at L’Orbiere, near Saumur. This is an extraordinary walk-in sculpture which penetrates the rock with a series of carved tufa cavities and tunnels, visceral in texture. A convex exterior work looks like the guts of the earth splurging out on to the surface.

Work is still in progress.If you want to stay in a cave, the Lallemand family in Troo (see text) offers a splendidly furnished two-bedroom “troglo-gite” for short holiday lets (00 33 5472 5787). In Vouvray, Les Hautes Roches hotel (00 33 4752 8888) offers the last word in rock-cut luxury with six troglo-bedrooms overlooking the Loire. Gites de France (0171-629 5035) has a limited selection of troglo-cottages in its brochure, and Brittany Ferries (0171-836 5885) also has a couple of semi-troglogites in its brochure.. VISITORS to the Hampton Court Palace Flower Show next week will probably be marking their show catalogues with a large asterisk next to the show garden by Leyhill Open Prison. For the last four years, prisoners and staff have created one of the best-loved exhibits at the Chelsea Flower Show. This year, they have escaped from its brutal overcrowding to the freedom of Hampton Court.

Their 1995 garden is an “inside out” affair, entitled “Del’s Fresh Produce Store” and featuring a miniature prison shop surrounded by edible and decorative greenery. It aims to give people some idea of the unsung value of gardening – commercial and therapeutic – inside prisons in general, and at Leyhill in particular. With only a short time to go before opening day, preparations at the prison are bubbling along nicely. “I’m quite nervous,” admits Jeff Goundrill, estates and gardens manager, as he steers his minibus through the prison grounds “Things are going very well except for the melons They should be two feet tall by now but they’re not. I hope the judges don’t mind them being a bit questionable.”
In the past, RHS judges have been generous with the medals, especially for the charming “Edible Garden” which won a silver gilt medal at Chelsea in 1991 by portraying prison life as a sort of horticultural Pilgrim’s Progress. “Most people don’t realise all the positive things that go on inside prisons,” says Jeff Goundrill, passing the modern accommodation blocks set in landscaped grounds. “So taking part in big flower shows at least gives us the chance to show the hard work of prisoners who work on the farm and in the gardens.”The view of the prison from here resembles the campus of a pleasant provincial university.