A palladian mansion on the shores of Strangford Lough has been home to the Montgomery family since the early 17th century. Hauntingly beautiful, Grey Abbey stands on a hill above the pretty eponymous village of Greyabbey on the Ards Peninsula.

This peaceful part of the North is still largely unspoiled - the Troubles of the past three decades have discouraged all but the most determined of tourists. A pair of bronze geese guard the entrance hall, which opens into a magnificent oak-floored inner hall lined with family portraits. The centerpiece of this room is a delicate cantilevered staircase sweeping up to a gallery landing.

"The house is a real luxury. When you have so much space you can afford to be convivial," says William Montgomery, known to his friends as Bill. He and his wife Daphne have lived at Grey Abbey for the last 30 years and Montgomerys have been here since 1604.

The name Montgomery has achieved new fame since their daughter Flora became toast of the town for her performance as Trudy in the film When Brendan Met Trudy. She plays opposite Jason Patric in Neil Labute's Bash, opening on March 27th at the Gate Theatre.

Bill is Sotheby's representative in Ireland and Grey Abbey is a suitably impressive base for entertaining clients. The house gives the family a feeling of being part of history, says Bill.

"Everything happened to my family. People went off to wars, were Members of Parliament, poets, went to America. Uncle William married Lady Betty Ponsonby who was Queen Victoria's private secretary. She was a great friend of Lady Gregory and a keen supporter of the Republican movement."

Bill's work with Sotheby's, his interest in historical houses and opera and Daphne's reputation as an excellent hostess mean the couple entertain frequently. The octagonal Strawberry Gothic dining room was added in 1782 by an earlier William Montgomery in honour of his wife Emilia's family seat Castle Ward, famous for having one classical facade and the other Gothic.

Ornate ceiling plasterwork depicts the arms of the Bangor and Montgomery families. There are six Gothic-shaped alcoves, three with windows draped in cream fabric and the fireplace is Kilkenny marble.

"The diningroom is my favourite room. It's staggeringly pretty, like dining under a magnificent tent. When the weather is fine, we bring the dining table and Persian rugs and all the silver outside. Sitting on the lawn outside is surreal, like being in a Magritte painting."

The ruin of the old 12th century Cistercian abbey across the park is used by the family on special occasions. "We have put on opera in the abbey ruins and our daughter Fouzel was married there. It was fantastic - the first wedding held there since the roof was taken off the chapel in the 18th century. We built an organ on scaffolding and it rained so much you could have floated ducks in the puddles in Fouzel's train," laughs Bill.

The family grew up with music and still sing in the Middle Drawing Room around the grand piano, bought by Daphne at an auction for £25. She also began a family tradition of going into the woods at Christmas to sing carols. Daphne's influence is everywhere, says Bill.

"We moved into the house together when we married. I was brought up here and I had the fun of bringing my children up here too. Daphne brought a new eye to the house. It was she who saw that the Gothic room would make a breath taking dining room . . . She had the vision to see how a house can change."

The downstairs windows of the house stretch almost to the ground, making every room full of light. Gold fabric lines the walls in the library, a cosy booklined room with comfortable sofas and easy chairs and family clutter on every surface. A drum on top of one of the bookcases was brought back from the Boer War by an uncle in the Scots Guards, and two fine bookcases hold some interesting family records. A hand-written Receipt Book dating from 1725 has horrific cures for croup and convulsions alongside recipes for raisin wine and seed cake.

"Grey Abbey was designed before electric light and planned so occupants can follow the natural light around the house. The kitchen gets morning light, the blue drawing room the midday sun, and evening sun streams in the library windows.

"Although the house is on a hill with views across the lough, there's another hill behind, giving shelter. There could be a gale blowing, yet we're in relative calm. Architects in the 18th century had the art of building to give absolute pleasure. The detail makes all the difference."

In the blue drawing room, an Irish sideboard built for the house in 1760 stands in an alcove decorated with plaster fleur-de-lys, in anticipation of a visit from George, Prince of Wales which never transpired. Underneath is a serving table from the days when this was the dining room. Most of the furniture was made specially for Grey Abbey when it was rebuilt in the 18th century, after fire destroyed the previous house.

The Montgomerys converted the present kitchen from a number of smaller rooms at the back of the house. A boot room, smoking room and shooting room were knocked together into one big green-painted room, with duck egg blue cupboards, thick beech worktops and twin Belfast sinks.

"The only bath in the house was in the boot room when I was a child, and all the food was carried up from the kitchen in the basement. I got fed up having cold food and carrying it all that way. We converted the wig room to a bathroom because it seemed sensible to have the bathroom upstairs rather than on the ground floor," says Bill.

Down the back stairs, the original kitchen area is a wonderful vaulted warren of rooms, with the main room now a busy laundry and sewing room. The old still room was converted into a billiards room and the butler's pantry is the new boot room. The stone stairs are indented from the footprints of servants scurrying up and down. Before the war, there were 16 servants in the house, says Daphne. Now they manage with one daily help.

A tunnel from the original kitchen area was the servants' entrance in the old days. This leads to a drying yard, a game larder, a couple of pretty workers' cottages, the stables and the dairy. A "home cow" used to be brought here daily for milking.

The curtains are drawn in one of twelve bedrooms on the two upper floors to protect a display of the former Lady Charlotte Montgomery's watercolours. She was a gifted painter, but neglected her eight children so badly they were reduced to begging for food from the servants.

Developing the gardens has been a major project for Daphne, who grew up in the Welsh Border region. The "haha" can now be seen from the house and she has regenerated the Victorian orchard, which contains ancient varieties of Irish apple. "The gardens had been allowed to go," says Bill. "The kitchen garden had become a paddock and the flower gardens grown over. Daphne has brought them all back with fabulous success."