The prospect of restoring a dilapidated 17th-century French estate and turning it into a thriving holiday business would be daunting enough for most people. Throw in the need to rescue a series of frescoes in the manor house and it becomes an even bigger ask.

But Ian and Theresa Martin did not hestitate to take the job on. “Although I don't really believe in love at first sight, the hair stood up on the back of my neck,” Theresa says, recalling the day in 1997 when she first saw Domaine de Peyloubère in Gascony.

The estate near Auch, the capital of the Gers region of southwest France, had a charm that survived even its rundown state. The Martins, who then lived in Clapham, South London, wanted a change - of lifestyle, career and climate - and to work together; he was then working in the City and she ran her own marketing and promotion business.

“It was the first place we saw on our viewing day,” Theresa says of Peyloubère. “We saw the potential even though it was tired and neglected. It took 30 buckets to catch the drips from the leaking roof.”

Peyloubère was also a listed building, exceptional not just for its architecture but also for its striking frescoes. In 1925, Mario Cavaglieri, an Italian painter, came to live there with his wife, Giulietta. It had a little too much rustic charm for her and she told him to create a little corner of Italy. This he did, painting Italianate scenes of myth and legend on the ceilings, walls and cupboards throughout one wing of the house.

“The frescoes were badly damaged,” Theresa says, “with fallen bits of plaster and flaking paint, so we obviously had to fix the roof first.”

With advice from an architect at the French heritage organisation Bâtiments de France, a special plaster was injected between the laths and the frescoed ceiling. Where the ceiling had bowed and separated from the laths, it was pinned. It was work for specialist artisans, so Ian and Theresa got on with cleaning, decorating and furnishing the five cottages on the estate. It took four years to get it all functioning as a chambre d'hôte - bed and breakfast - and holiday cottage business.

Meanwhile their son, Max, started at the local school. “He was used to French but by no means fluent. When he arrived he was the only foreign student. He had celebrity status for about a month and then everyone just got on with being kids,” Theresa says.

The frescoes were finally restored in 2002, and rental on the gîtes was going smoothly - so they began work on the gardens, lake and woodlands of their 35 acres. Ian says: “We have been fortunate to have five cottages to let as well as the two chambre d'hôte rooms because it gives us economies of scale. It's very hard to make any kind of revenue when there's just one cottage.”

But old buildings are never just about figures. “We've had tremendous fun as the connection with Cavaglieri has strengthened,” Theresa says. “People in the village have told us stories about the artist, and many have small portraits painted by him. Before the Second World War, photographs show Mario in a dinner jacket clutching a glass of champagne. A highlight was visiting a recent exhibition of Cavaglieri's work in his home town of Rovigo, northeast Italy. For the first time we saw many of the paintings of the house that he had painted at Peyloubère.”

Now that Max, 20, has left for university, the Martins are ready for their next challenge. Ian says: “We'd like to build an environmentally friendly house from the ground up using a lot of the techniques that we have learnt during the restoration. There's a limit to what we are allowed to do with a listed building.”

Domaine de Peyloubère is for sale for €3.3million. Go to peyloubere.com

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