His father introduced internment to save 'his beloved Ulster', but Mike Faulkner never felt rooted in the North until he returned to the family holiday home, he tells Susan McKay.

He is, he happily admits, a "frustrated cowboy". Not long before his furniture-making business went bust, Mike Faulkner transformed the Edinburgh back alley where he had his workshop into a film set for a western.

"We had the whole John Ford: saloon, grain store, log house, cantina, livery stables, railroad station and, of course, a sheriff's office," he says. It was, he agrees, "misjudged and costly" but it was "hugely enjoyable."

"Sometimes," he writes in his new book, "I worry about myself." As well he might. He describes his career making "Santa Fe"-style beds as having been an "opportunity to indulge myself". It followed "brief excursions into law and property". All were doomed.

Faulkner's book, The Blue Cabin: Living by the Tides in Islandmore, begins with a poignant description of the leaving of Quilchena, the old stone farmhouse in central Scotland that he and his wife, Lynn McGregor, had, in the course of a decade, turned into their ideal home.

"We thought we'd spend the rest of our lives there," he says.

That was 2002. The business was in ruins and Faulkner had finally been forced to admit he had stumbled into insolvency. The house had to be sold. The future was a "freefall into darkness". Not really, though. There was "a convenient island paradise - secluded, uninhabited and rent-free" to which the couple could escape.

This was Islandmore, where Faulkner's mother, Lady Lucy (of Downpatrick) had a house. The island is one of many on Strangford Lough, a five-minute boat run from the Co Down mainland.

This had been the family's holiday home. Mike Faulkner's late father, Brian Faulkner, was Northern Ireland's sixth and last prime minister, and this was the place to which he used to retreat with his family for weekends and summer breaks in the late 1960s and the first half of the 1970s, while the Troubles raged and burned. The family was wealthy - Brian Faulkner had a managerial role in his father's factory before he became minister for home affairs in 1959.

"At home the phone was always ringing and there was a very heavy security presence," says Mike Faulkner. "I saw my father as much on TV as in the house. He only really relaxed when he was on a horse, on a boat or on the island with the family. He used to sit out on the veranda on Islandmore reading Somerville and Ross, completely at ease." He loved to watch Kojak on television, too.

Faulkner's father is his hero. "He had no guile . . . he offered transparent straightness and a focus born of passionate conviction," he writes. If Faulkner is aware that others may regard the glimpses his book gives of his father in a different light, he shows no sign of it. For example, he admires his father for scheduling cabinet meetings so as to allow him to go out hunting with hounds on winter afternoons.

Adopting the noble but aggrieved stiff-upper-lip tone of the 1970s Big House unionist, Mike Faulkner, who was a teenager at the time, describes in his book his father's efforts to save "his beloved Ulster". The police and the UDR were, he writes, dealing with the security situation with "professional restraint". Those charged with guarding his father are avuncular types, loyal and true, winking and smiling and hiding sweets for the children in a tree in the grounds of Highlands, the family mansion in Seaforde, Co Down. One of them allows young Mike to fire his .22 rifle, but the boy misses the target.

In later years, one of the policemen confides in the author about those troubled times: "The best years ever a man had and they'll never come again." For his father, the introduction of internment without trial in 1971 was, Faulkner writes, an "appallingly difficult decision". He claims his father conscientiously read many of the security details on those about to be interned. He doesn't say that many internees were innocent of any involvement in "terrorism", that internment caused widespread nationalist alienation, that unionism was seen to be out of control or that Stormont was about to fall. He recalls, as if it were entirely shocking, that his father received a message from Long Kesh Prison which said simply: "Dear Brian, Merry Christmas. Wish you were here."

It comes as no surprise to learn that Faulkner jnr has "no interest whatsoever" in politics, "apart from my father's career, in which I am emotionally invested".

"He was by nature democratic and fair and he went on to lead a power-sharing executive which included much of what was later included in the Good Friday Agreement. But at the time of internment he was under tremendous pressure to do something about terrorism. He taught me that it was sometimes better to do the wrong thing than to do nothing."

THE ISLANDMORE HOUSE consists of two wooden huts which started off housing German prisoners of war at an internment camp in the Isle of Man, before being sold in 1919, and shipped to the island.

The house was used infrequently in the years after Brian Faulkner's death in a riding accident in 1977.

"Lynn and I arrived off the boat at the jetty and the cabin had a ramshackle, welcoming, port-in-a-storm sort of look that said 'come on up, I'll take care of you'," Mike Faulkner recalls. "Morale was low. I felt guilty because it was my business that had failed. Bankruptcy was looming. But as we looked back at the mainland we felt as though the drawbridge had been raised. We didn't have to explain ourselves any more."

The house was cluttered and shabby. Faulkner's childhood bedroom was as he had left it, complete with psychedelic poster and broken fishing rod.

It was cold and damp at first, but Lynn, a professional artist, is also a gifted interior designer, and before long she set about transforming the place. Faulkner made some of the simple, elegant furniture. It is lovely now, all driftwood, cotton and candles.

"We thought we'd stay at most a year, and it rather surprises us to find we've been here for four," says Faulkner. "My family has been very generous," he says. Lynn now has a studio - a tiny garden shed.

Faulkner says the high point of his life was his teenage experience of a ranch in Canada. In Islandmore, though, it has been the decision to write.

The Blue Cabin is an odd book. Sometimes it seems as though Faulkner has come back to be a child again. He left Northern Ireland to go to boarding school in Scotland in 1974 and stayed away. Times he spent with his parents and brother and sister on the island are lovingly recalled. There are descriptions of storms and sunsets, and picnics with friends with nicknames such as "Puddleduck" (from Beatrix Potter). There are reflections on life, and a few "local characters" are sketched.

Faulkner does not spare himself in funny anecdotes about foolish adventures. Disarmingly, he admits that as well as being "a little inarticulate, a lot shy", he has also always had the "sneaking feeling that I was never the sharpest tack in the stationery drawer". Islandmore has taught him, he says, that there are other ways of being intelligent.

He sent off the manuscript of his book to get pre-publication "blurbs" and heard back from, among others, Senator Maurice Hayes, who describes it as "a prose hymn to Strangford Lough . . . with a dash of The Good Life". Faulkner and his wife and family have high hopes that the book will mark the start of another new career.

The couple will probably go back to Scotland some time. "Lynn is very rooted there and I am not rooted anywhere . . . We thought when we lost our home it was the end of the world. This has been a place of healing for us."

• The Blue Cabin: Living by the Tides on Islandmore, by Michael Faulkner, is published by Blackstaff Press, £7.99.