|The Rowan Hamiltons with three of their children, from left, Willa, Jake and Charlie|
When Lt Col Denys Rowan Hamilton handed over the keys of Killyleagh Castle to his son five years ago, he reassured him that he mustn't let the property become a millstone around his neck and that, if it ever became too great a burden, he could sell it.
Then, on his way out the door, he reminded him gently that the castle had been in the family for 400 years.
"It was a bittersweet moment," Gawn Rowan Hamilton ponders, sitting in a cosy but strikingly high-ceilinged room in the oldest inhabited castle in Ireland.
"But I always knew, growing up, that if things worked out I would come and live here. I also knew that I had to earn a living to be able to afford its upkeep as, unfortunately, the castle isn't surrounded by masses of land.
"The handover went very smoothly and it is a far nicer place to raise a young family than London, where we used to live."
It certainly seems like an idyllic existence for Gawn, his wife Polly and five children Tara (10), Archie (9), Jake (7), Charlie (4) and Willa (3). There is endless scope in the nine-bedroomed castle for searching for secret passages and the several spiral staircases leading to the top of the towers provide hours of fun. The castle even has its very own dungeon.
And outside, there are enough lawns to host Wimbledon and a swimming pool worthy of any Olympics.
Built in 1180 by John de Courcy as one of a series of fortifications around Strangford Lough to protect against the Vikings, the castle, with its handsome turrets and seemingly impenetrable walls, looks like it has been lifted straight from the Loire valley. The constant stream of tourists, who gaze in wonder through its iron gates, compare it to Hogwarts or a castle from Disney.
It has been kept in excellent repair through the years and, says Gawn, only needs painting on the inside - although that's not going to happen any time soon because of the children.
Even the nursery is the same as when Gawn was a child, and now his children are enjoying it too.
Gawn, who is his father's only son and has three half brothers, one half sister and two full sisters, attended Killyleagh Primary School and his closest friends lived on High Street. He was then sent to Eton and after that studied at Cambridge - but returned to the castle at every opportunity.
"Family stands out most of all from my childhood memories," he says.
"I am the youngest of my mother's seven children and the house was always full of people. I remember sitting around the dining room table with a very large family having quite intensive discussions and arguments.
"Because I was at boarding school, mum would compensate by asking people to stay when I came back for holidays, and she didn't mind if there were 10 or 20 people for lunch. She was determined that we would have a good time here.
"And because it was known that I was going to come and live here one day it made it easier on the others."
What was it like, living in a castle?
"Up to the age of 14 I wasn't aware of the significance of living in a castle," Gawn says. "You think you're lucky but you just take it for granted.
"I went to Eton so living in a big house didn't distinguish me at all, but one hopes my children will be comfortable with it. If they are comfortable with it then they will take little notice of what people think."
As Gawn spends half of each week in London as director of a major mergers and acquisitions firm, Polly spends much of her time looking after the castle, its self-catering accommodation in the gatehouses and events it hosts such as outdoor concerts - Van Morrison has played here - and plays (including The Merry Wives of Windsor on August 12).
The family conducts tours for schools and, with the castle holding a registry licence, weddings also take place.
"I just love Killyleagh and the sense of community," says Polly. "It's so much nicer than London, the people are wonderful and because the house is right in the village we feel part of everything that's going on."
Indeed, the Hamiltons have been part of goings-on for some 400 years since, in 1606, in an event described as the most important in Ulster Scots history, Gawn's ancestor James Hamilton and his fellow Scot Hugh Montgomery arrived.
Montgomery had spied his opportunity to acquire a chunk of eastern Ulster when Irish chieftain Con O'Neill was imprisoned and needed his help to escape from jail and secure a Royal pardon from Montgomery's friend, King James I. But Hamilton discovered the plan and persuaded O'Neill to give him some land, too, a move that caused the Scottish settlers to become bitter rivals despite living close to each other in northern Co Down.
When he settled in Killyleagh Castle, James Hamilton built the courtyard walls and then his son, the first Earl of Clanbrassil, built a second tower as a sign of rising prosperity.
In 1649 the castle was besieged by Cromwellian forces, who blew up the original gatehouse using gunboats which had sailed into Strangford. The Earl fled, leaving behind his wife and children. A staunch supporter of the Crown, parliament fined him all his spare cash for the return of his castle and land.
But contrary to what their history might suggest, the current Hamiltons and Montgomerys - whose country seat is Grey Abbey House in Co Down - are good friends.
"I grew up with the Montgomerys and it makes me laugh when I think that when the two families first arrived here they fought battles with each other," Gawn says.
"I suppose Montgomery felt slightly cheated out of the sweet deal he had concocted with Con O'Neill and probably felt quite bitter. When he was on his death bed he decreed that no Montgomery must ever marry a Hamilton and to this day I don't think the families have intermarried.
"I find that astonishing, actually, given the fact that we have lived beside each other for 400 years."
For centuries the castle's first role was protection but in more recent times work was done to make it more comfortable.
"During the famines in the 1850s my great-great-great grandmother redeveloped the house and installed gas," Gawn says.
"Because she received no income from the state she decided to spend all her maternal fortune on making the house habitable.
"She employed Charles Lanyon, the architect of Queen's University, Belfast, to redesign and open up the castle."
This was a challenge for Lanyon, who was used to building on a greenfield site - but the castle was confined to a structure already in place which he couldn't change. But he made sterling work of it nonetheless, and all the intricately detailed plasterwork and wood panelling dates from this period.
"Lanyon turned the castle from what would have been a dark and uncomfortable interior to a very light and comfortable one," explains Gawn.
"And although people might think the castle is cold and draughty, the rooms are actually not as big as you may imagine because the walls are so thick."
And with all that colourful history, there must be a ghost or two, surely?
For instance, does the so-called Blue Lady, Lady Alice Moore, flit through the corridors at night?
She was married to the second Earl, Henry Hamilton, and their only child died in infancy.
To her horror, the first Earl had decreed in his will that if Henry died without issue the estate should be divided between five cousins. But in her determination to get her hands on the Hamilton properties for her own family, Lady Alice destroyed this will and made her husband write a new one. Henry received a letter from his mother with the grim warning that the day he changed the will would be the day he died. So it proved, as Henry was poisoned by his wife shortly after bequeathing his estate to her.
"Yes, I suspect there are ghosts running around with tales to tell," says Gawn. "Although I haven't seen a ghost people say that some rooms are spookier than others. It certainly adds to the character of the castle to think there might be ghosts."
There have been explosive events more recently, too, for the castle was targeted during the Troubles in the 1920s.
"I have a cutting from the Belfast Telegraph which tells the story of my great-great uncle being woken at 2am and exchanging gunfire from the battlements, which was terribly exciting," says Gawn.
But, despite the family's history of settling on land once owned by Irishmen, Gawn says the Hamiltons have never experienced animosity from Roman Catholics.
"Actually, my most famous ancestor was Archibald Hamilton Rowan, who was a United Irishman," he explains.
"He was put in prison by the British in Dublin but escaped and went to the America before he was pardoned and returned.
"There was one occurrence of animosity from loyalists in the 1970s when my father stood for election to Westminster as an Alliance Party candidate.
"Although he didn't get in loyalists were angry as they believed he was establishment and was taking some of their votes, and they burned his effigy in one of the village estates. That shows how extreme the politics of that time were."
A happier event concerns the Baron of Killyleagh, Prince Andrew, who regularly visits the village, although he hasn't stayed at the castle during Gawn's tenure.
"My father was hosting an event one day which the Duke of York was attending," he says.
"A wedding had been booked for that afternoon and, because the first event was running longer than expected, my father eventually had to tell the Duke that he had to go as the wedding party would soon be arriving.
"Of course, on their way out the Duke and his entourage bumped right into the wedding - but he jumped out of his car and went over to the wedding party and had his photo taken with them, which was very good of him."
With the 400th anniversary celebrated this year, the family hopes that there will be many more in the future.
"To have such a long history of the family here is wonderful and that sense of continuity reinforces the feeling I have about the house," Gawn says.
To celebrate the 400th anniversary of the Hamilton and Montgomery settlement of 10,000 Scots families into Counties Antrim and Down, the Ulster-Scots Agency is hosting a Dawn of the Ulster-Scots family folk festival at Rosemount Estate, Greyabbey, tomorrow from 10am to 8 pm.
There will be a fantastic line-up of Ulster-Scots music - folk, gospel, bluegrass, pipe bands and drumming - with Willie Drennan's Ulster-Scots Folk Orchestra headlining. There will also be a 'kids zone' with everything from inflatable megaslides and bouncy castles, to face-painting and crazy golf, along with traditional games, archery and falconry.
The finale, at 7pm, will be a performance of 18 Miles to Freedom by the Valhalla Players, which tells the story of the Scots settlers.
Admission is free but there may be nominal charges for parking and some children's amusements. Check www.ulsterscotsagency.com or www.HamiltonMontgomery1606.com for further information