Back in 1999, Liccy Dahl “was longing for somewhere with peace and quiet, where I could escape”. Since the death of her husband, Roald, the children’s writer, nine years earlier, life at Gipsy House, the home they shared in Great Missenden, Buckinghamshire, had become busier than ever. “Work, children, family – chaos,” says Liccy (pronounced Lissy, and short for Felicity). It was “like Paddington station”, the “terminus” for six grown-up children (from previous marriages) and the grandchildren – including the model Sophie Dahl – who now total 13.

“I wanted a house in Italy for peaceful moments,” says Dahl, 69. So why did she buy a derelict chapel in a fishing village on the south Cornwall coast? “I saw it advertised – Grade II-listed, with planning permission – and thought, ‘If only that was in Italy.’ But sometimes in life you have to compromise.”

Dahl’s first trip to Portloe should have turned her attention back to Italy, sharpish. While the handsome 1843 building offered wonderful views over the village and the voluptuous coastline of the Roseland peninsula, it had “no amenities, no access, nothing”.

“But I could just tell it was fantastic,” she says. So it was off to the auction, and the property was hers – though for considerably more than the £100,000 guide price. “I was buying a nightmare,” Dahl says cheerfully.

With faith in her own vision, a sound instinct for choosing the right people and a budget of £250,000, the Old Chapel was transformed, within a year, into the living space she wanted: “quiet, open and light”.

Steve Duckham, a local builder, and his two sons turned out to be equal to the task of transforming into reality the plans of Mike Hitchings, an architect who lives in the village. They had help from the “terribly tolerant” closest neighbours in the terrace of fishermen’s cottages, who allowed access through their drive and garden.

“Even so, I don’t know how they got the scaffolding down there,” Dahl says. “It’s just a footpath. They brought in great slabs of granite for the terrace, and the three of them carried the beam for the drawing room from the main road. They were used to it – that’s Cornwall.” There’s still no parking: you leave your car in the car park (with honesty box) and walk down the path.

She had to work within the constraints of the building’s listed status. The roof was restored with slate tiles and services were connected; the lower ground floor became two bedrooms and bathrooms with Victorian-style fittings, including high-cistern loos; the upper floor became an open-plan kitchen and living area, 40ft x 25ft, with a mezzanine.

The original wood floor was raised by a couple of feet, so you can look out of the elegantly arched windows – they were placed high so the faithful could not be distracted from the sermons by the view.

Dahl brought in one of her daughters from her first marriage, Charlotte Crosland, an interior designer, to plan the inside spaces. Interior decoration is a shared family passion: Dahl herself founded the Carvers and Gilders company, and her other daughter, Neisha Crosland, runs a textile and wallpaper design company, though none of her fabrics found their way into the Old Chapel. “It’s a seaside house, so you can’t have silks and damasks – in fact, there are virtually no fabrics, except the sofas and cushions,” Dahl says. “The windows have shutters.”

She describes her style as “slightly Nordic” (Roald’s parents were both Norwegian, and she loved his sisters’ interiors ideas), or “English without the chintz”. The house is rescued from austerity by the invitingly comfortable sofas, the honeyed gleam of the wood floors and a confident use of colour, from the coral-red front door (from Papers and Paints) to the pretty “reseda” appley-minty green bedroom walls (from the Paint & Paper Library).

And outside? The Old Chapel has only a terrace at the front (west-facing, for viewing the glorious sunsets), a small garden at the back and an outdoor shower with ferns growing from the rock face: a practical idea after an afternoon at the beach. Yet Savills, the selling agent, has valued the place at £750,000, reflecting the unrelenting demand for holiday homes in the area.

Dahl is selling because life has not stopped being busy. When she is not doing showbiz deals – the director Wes Anderson will be filming Fantastic Mr Fox, and a stage musical of Charlie and the Chocolate Factory is in development – there is the Roald Dahl Foundation, a grant-giving charitable trust, to look after. Planning is in full swing for the third annual Roald Dahl Day on September 13, involving schools, libraries and bookshops.

Family life still fills Gipsy House – and there are just not enough gaps in the schedule to get to Cornwall for that elusive “peace and quiet”.

“It’s an escape – with privacy,” Dahl says. “Nobody can come on that terrace, nobody comes past. Roald would have loved it, though he’d have hated the walk from the car park.”

Savills: 01872 243200, www.savills.com ; www.roalddahl.com

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