La Chevalerie du Fieffe Noble is set in glorious rolling Normandy countryside, half an hour from Cherbourg. Life passes peaceably, there's hardly a soul on the roads and beaches are populated only by people winkling or musseling. It is five miles from the village of Ste Mère-Eglise, renowned for the part it played in the D-Day landings - a parachutist got stuck in the bell tower.
Margaret was no newcomer to doing up property - she'd done it in the UK and abroad for 30 years - but this time she was looking for a holiday home for herself and her partner, their children and grandchildren.
"I particularly wanted to be near the sea and wanted beaches with nobody on them and somewhere with a good climate, but not too hot. Normandy or Brittany fitted the bill," she says. She also wanted something that had hardly been touched. "I had to have that magic quality," she says.
Seven years ago, Margaret started searching on the web from her home in Oxfordshire. "I looked at many properties, and every so often chose three out of hundreds, but every time I made enquiries someone had bought the house."
Then, while she was staying at a B&B in Barneville-Carteret, she read a book about ancient houses in Normandy. The owner told her of an Englishman living next door who could oversee any project she took on.
"A year later, I still hadn't found anywhere, so I rang the B&B lady and she gave me his number. He told me he would love to supervise the work and I told him he had to realise it was my project. We came to an agreement, but I still hadn't found a property," Margaret says. The next week, she went to Normandy to have dinner with him. He showed her the details of two properties that had been faxed over. "One was perfectly appalling, with lots of turrets. The other was a plain Norman house with a completely flat front. I said, 'That's the house we are going to buy," she says.
The next day, Margaret went to see the house. It was a beautiful sunny day. "We got to the bottom of a great field and had to take the car through very long grass. When we got to the top, there was this beautiful shell of a building with a roof, but not much else.
"The windows were broken, the shutters were hanging loose, there was only cold water and no electricity. But the great hall had the most beautiful fireplace you have ever seen. It was total magic." Ten days later, it was hers.
It took two years to transform this wreck of a house into the beautiful home it now is. Now, nothing leaks and everything works. Water, electricity and gas were piped in at considerable expense, although the garden is watered by the well which, sadly, does not provide eau potable. Margaret had to put in new floors upstairs - none had survived by the time she bought the house. On the top floor, she has created two family rooms at one end and a double room at the other and, below that, another four bedrooms.
The doors, some of which dated back to the 1600s, have been restored and the downstairs walls are finished in the same lime plaster as they would originally have been.
The kitchen, which looks old-fashioned because Margaret has used old cupboard doors and materials, has a modern range and all the necessary appliances. The beautiful slate floor was sourced from an architectural reclamation company in the Loire.
The great hall, which originally had an earth floor, is now the games room, with billiard and table-tennis tables. It can also be used as a dining room, as the billiard table converts into an ordinary table. With the vaulted ceiling, it is an extremely impressive room. The floor is now concrete with an inlay of cobbles. The garden has been totally created anew, using cuttings and "babies" from many of the plants in Margaret's garden in Oxfordshire. She's grown all the box hedging and planted many trees, including those in the apple-lined avenue up to the house.
In the 3.7-acre grounds is a fascinating shell house, which Margaret designed with the help of her young friends and family. "This is my pride and joy," Margaret says. "It's a square-shaped Norman house with one side open.
"Because of the name of the main house, the shell house has a horse on the top, which was made by a potter in Barfleur. I have collected shells all my life and with more shells from all over the world that friends have given me, we have created a huge sea-horse on one wall.
"On either side there are large rearing horses and then there's the sun and moons, terrapins, birds and butterflies. The last horse is a river horse, another name for a hippopotamus. We must have used about 28,000 shells in all."
Get the spec
What's for sale:
17th century manor house, beautifully restored with seven bedrooms, six bath/shower rooms, four reception rooms and fabulous grounds.
Serious kit: The hall is now a vaulted games-room; period flagstone floors; the housekeeper is prepared to stay on.
How big? 425 square metres standing in 1.5 hectares of grounds, including orchard and meadow.
Extras: Seven barns that are ripe for conversion. One has planning permission for a one-bedroom cottage and a shell grotto in the garden.
Buy it: La Chevalerie du Fieffe Noble, Normandy. Price €1.25m (about £849,000). David King & Associates, 020-8673 6800