Magna Carta Island goes on sale

Property for sale: in need of modernisation. Six bedrooms. Large dining room. Reception. Breakfast room. Swimming pool. 402m of riverbank. A moat. And a Charter Room housing the stone on which Magna Carta is believed to have been sealed on this very spot in 1215.

Househunters craving original features and a sense of history (at least those with a £4m-plus budget) could do worse than Magna Carta Island, a 3.725-acre residence on the banks of the River Thames which Sotheby's Realty claims "is widely acknowledged to have been the site of the signing of perhaps the most significant charter in history," paving the way for liberty and the established rule of law in England and Wales, and forming the basis for the Declaration of Independence in the United States. Boasting a main house, cottage, double garage and nearly four acres of gardens, the island is accessed, surprisingly, by land.

Visitors arriving from the main road, three miles from Staines, approach from the north bank past the Ankerwycke Estate, on which, explains Graham Cooper, its current owner, stands the remains of a nunnery where Henry VIII is reputed to have courted Anne Boleyn – offering a neat segue to the rich history of the island itself, which stands beyond a bridge accessed through a small woodland.

Magna Carta Island was privately owned until Sir Patrick Hannon, then chairman of the industrial combine Birmingham Small Arms (BSA), who had bought it in the late 1920s and restored the house and gardens to their former glory, gave the property to Buckinghamshire County Council in the days before the land became part of Berkshire.

"They didn't seem to know what to do with it," says Mr Cooper, who has lived here on and off since his parents bought the place in 1967, when he was 20. "There was a succession of tenants; last of all an American authoress called Miss Bigelow who had many poodles. Whenever someone came to collect the rent, she set the poodles on them. When she left, they let it lie fallow."

That was until the Coopers bought and revamped the place. It became the location for many a grand do hosted by the late Mrs Cooper, Graham's mother, "a tremendous party animal".

"She was a very keen car enthusiast who became a member of the Maserati owners club and would have a party at start of each season," Mr Cooper explains. There would be 40 vehicles parked in the driveway and revellers spilling through a huge hallway with its inglenook fireplace, and the same timber stairs that still lead to the Magna Carta room with its stained-glass windows, wooden beams, the painted crest of the barons looming large from the walls – and in the middle, the inscribed stone, celebrating the signing of the Great Charter.

Today, the dining room stands to the right of the same hallway with wood panelling, a grand stone fireplace and arched windows overlooking the terrace with its swimming pool, and extensive lawns tumbling down towards the water. In the summer in which the Coopers first moved in, they would look up from their lunch table and see families piling onto the grass with rugs and baskets for a riverside picnic, believing it still to be public land.

As well as the main house, which was built in 1834 by George Simon Harcourt, Lord of the Manor and then Sheriff of the County, a second cottage and double garage are part of the residential bundle, as well as a private mooring, built by Graham Cooper's father "so the Queen could land with ease and in sufficient grandeur" when she came to plant a walnut tree in the grounds as part of her River Progress in 1974.

It is "the provenance of the island", says estate agent Stuart Cole, that made it hard to value. "If you took it in isolation in the locality it would be worth much less than this. But [Sotheby's auction house] sold a copy of the Magna Carta for $20m recently, and that was just a piece of paper."

Whether King John, who met his rebellious barons in 1215 to seal the document widely regarded as the cornerstone of liberty in the English-speaking world, authenticated the deed here or on the mainland, is up for grabs.

Dr Louise Wilkinson, a reader in medieval history at Canterbury Christ Church University, explains: "All we know is that Magna Carta was sealed [not signed, which is a common misconception] by King John in June 1215. As to location, the 1215 charter itself says, it was 'given by our [King John's] hand in the meadow called Runnymede, between Windsor and Staines, on the fifteenth day of June in the seventeenth year of our reign'.

"I am not aware of any strictly contemporary evidence linking it specifically to what is now called 'Magna Carta Island," she adds, "though "it is very close to Runnymede."

Indeed, some experts question how great the charter really was. In his book A History of Britain, Simon Schama argued that Magna Carta – which focused on rights relating to barons – was not the birth certificate of freedom but rather the death certificate of despotism.

Nonetheless, with a guide price of £3.95m, Stuart Cole believes the island will soon be snapped up. "The phone has not stopped ringing," he says. "We've had calls from famous people and people around the world. "We think someone from an American legal company will be the eventual buyer – they are so tied into how [Magna Carta] built their constitution," he adds.

Whoever bags it, Graham Cooper believes will be a lucky soul: "It's a wonderful, warm friendly house with wonderful karma. I am single, retired, the house is far too big for me. When I go it will be a very sad day but there comes a time when it's time to move on."