CHAILEY MOAT, near Lewes in East Sussex, is a moated house with a difference: it was built not for defence but as “a mansion of peace” for an 18th-century rector. However, the present owner, Stephen Cotton, a former fund manager, has found even older foundations and believes the house to have been a fortified medieval farm. He is a trained surveyor, and built a teahouse for Lord Snowdon that stands on stilts in a lake on the Nymans estate in West Sussex.

“This is the perfect place for a sundowner,” he tells me at Chailey as his wife, Jo, brings out an ice-cold elderflower cordial on a baking-hot afternoon. “When we arrived there was a gravel sweep just across the moat. We did not want to sit looking at parked cars, so we replaced the gravel with a paved fountain garden.”

Today there is a mood-changing sense of arrival before you even glimpse the house. The walk there takes you down an arbour of pleached limes, trained over iron hoops and along bamboo struts. “It’s a technique I learnt from a country house hotel in Devon,” he says. Beside the fountain garden he has made a still grander gesture, forming a new lake fed by a passing stream. As the law now requires that any watercourse leading to the sea must be accessible to spawning fish, it comes with a “fish ladder” – a series of wide, deep steps, each three bricks high, challenging the fish to jump up to the lake.

Medieval moated castles usually have only a single bridge or drawbridge. Chailey Moat has three footbridges with sides similar to level-crossing gates. This makes it easy to slip across into the garden in any direction. On the fourth side a terrace opens off the kitchen, providing the perfect place to breakfast in the early-morning sun. Across the moat are beds of cocquiriam roses with huge blooms tinged with pink and yellow. “They go on flowering all summer,” says Jo.

Tile-hung houses are one of the delights of Sussex. Here the russet-coloured tiles adorn a pretty mid-18th-century front with a central Venetian window. There are handsome panelled rooms, and some of the windows have unusual shutters that slide back into the walls.

The plan of the house is deep, but it does not seem dark, partly because of the french windows that light the long kitchen. There is a pine-lined walk-in fridge. “If you get bored, you can turn it into a sauna,” he says.

All the bedrooms have lovely views because of the surrounding moat. The main bath has head cushions at either end for extra comfort. Elsewhere, lead trays have been placed beneath the new showers to avoid flooding.

Every room and outbuilding has been put to work. The old piggery is now an American-style two-bedroom guest cottage by the lake. Beyond, the shed for garden machinery has a smart cedar, shingled roof. The tithe barn is half-garage, half-cottage extending into the space above the cars. The orchard has been planted with oak, ash, maple and local trees.

The diocese sold the rectory in the late 1930s to a Royal Engineers major, Cyril Pekitt, who asked the Lewes architects Wratten and Godfrey to modernise the house. They and the Cottons respected the magic of the place. Long may this continue.

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FACTFILE

WHAT YOU GET: Grade II listed moated former rectory with five bedrooms, two cottages (one in converted tithe barn), lake, 43 acres. In all 6,391 sq ft.

WHERE IS IT: Six miles from Lewes and Haywards Heath (Victoria/London Bridge 50 min by rail), 20 miles from Gatwick.

PRICE: £3.5 million through Humberts, 01273 478828, www.humberts.co.uk

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