For most, the dream of transforming a derelict historic property is just that—a dream. But for Mike Conner, a former software company owner, it became a five-year odyssey that would see a crumbling Napoleonic fortress off the Welsh coast reborn as one of the UK’s most extraordinary party destinations. Thorne Island, perched just off Milford Haven in Pembrokeshire, has gone from abandoned relic to a £3 million party island, complete with nightclub, helipad, and panoramic sea views.
The story begins in May 2017, when Conner, then 52, purchased the 19th-century fort for £555,000. According to BBC News, the building had sat empty for 17 years, its once-bustling halls silent and its stonework slowly succumbing to the elements. The fort itself was originally constructed in the 1850s, designed to house 100 men and to protect the strategically vital port of Milford Haven from potential French naval attacks. The idea for a fortified island was first floated in 1817, but it wasn’t until after 1852 that the grand structure finally took shape, with as many as a thousand men laboring for two years to complete it.
After World War II, the fort’s military purpose faded. In 1947, it was converted into a hotel, quickly becoming a hotspot for birthday parties, weddings, and stag celebrations. But by 1999, the party was over, and the property changed hands. The Von Essen hotel group acquired it in 2001, with grand plans to spend £4 million reopening the hotel and even adding a cable car to the mainland. Yet, those dreams never materialized, and the island slipped into dereliction once again.
When Conner took over, he faced a daunting challenge. “I really didn’t know what I was getting myself into,” he told BBC News. The fort had no electricity, no running water, and every bit of food or waste had to be ferried back to the mainland. His wife, understandably, was less than thrilled at first. “She said she would stay once it had a flushing loo, which is pretty reasonable.” That seemingly simple request turned into a mammoth task—installing the first flush toilet meant cutting through 16 feet of solid rock to reach a biodigester pump, a job that alone cost £200,000.
Renovating Thorne Island was never going to be straightforward. Six men lived on the island for about four years, working in two-week shifts. “They would charge their phones with a generator and would have to have a dip in the sea for a wash. It was tough living,” Conner said. With no road or dock, most building materials and equipment had to be delivered by helicopter, a logistical headache that only added to the project’s cost and complexity.
Yet, against the odds, Conner and his team pressed on. The first year was spent simply making the place habitable. Over the next four years, the transformation accelerated. Today, the fortress boasts 40 beds, four en-suite bathrooms, a state-of-the-art nightclub, and its own helipad. The accommodation stretches over 8,000 square feet, with a grand entrance hall leading to open-plan reception, dining, and sitting rooms featuring vaulted ceilings, exposed brickwork, and double-aspect sash windows. The kitchen is modern and open, with an adjoining snug and sweeping sea views, as described by estate agents Strutt & Parker in the property’s listing.
Despite its luxury touches, Thorne Island remains completely off-grid. According to The Independent, it now features a range of renewable energy systems, including a photovoltaic solar display with a 100 kWh battery storage, air source heat pumps for hot water and underfloor heating, and a massive 250,000-litre rainwater harvesting system. Guests are encouraged to take their waste back with them—“no one comes here to collect the bins,” Conner quipped—making the island not just a party haven, but a model of sustainable living.
For Conner, the design process was the most exciting part. “I felt my task was really modernising it,” he said, describing the project as a tribute to the original Victorian builders. “It almost feels like a tribute to their hard work and you’re just really building the last little bit on top of what was already an awesome, bomb-proof construction.”
The island’s isolation has become one of its greatest assets. With no neighbors to disturb, Thorne Island has hosted everything from 80-person parties to tranquil retreats. For his 50th birthday, Conner threw a festival complete with a tight-rope performer traversing the courtyard. “With something always going on, people tended to put their phones away. I think that’s what makes Thorne a special place, that people are present,” he reflected.
As the project neared completion, Conner found himself letting go of the routines that once defined his life as a CEO. “We all often live by a calendar of scheduled meetings, but the island is the complete opposite—it’s off grid. It feels real time, it feels like living.”
Now, after pouring five years of sweat and vision into the island, Conner has put it back on the market for £3 million as of August 17, 2025. He hopes the next owner will appreciate the property’s unique potential. “It’s a blank canvas, and the next owner can work out what it’s for,” he said. He envisions the site as a tourist attraction or as the venue for “the most unbelievable raves,” with the ability to host up to 800 guests for 24-hour experiences. “If it was generating revenue, and creating jobs and sustaining itself, that would be a great outcome. The more people who could use it the better, as it’s got to be one of the most interesting buildings in the area.”
Conner’s journey with Thorne Island has been as much about personal discovery as restoration. Originally from Gloucestershire, he discovered during the process that he is a quarter Welsh, with his mother having grown up at Upton Castle, Pembroke Dock. The project, he admits, has been “incredible”—a parallel life of chaos and creativity, especially during the isolation of the Covid pandemic.
As the sun sets over Milford Haven, Thorne Island stands ready for its next chapter, a testament to perseverance, vision, and the enduring magic of Wales’ historic coast. For Conner, the work may be done, but the island’s story is far from over. “If there are any events there, I would crawl over broken glass to get there.”
