The new owners of Athlone House have pledged to restore the mansion and say they will not dig a basement underneath, the Highgate Society has been told.

It was revealed last week, as the Ham&High went to press, that the neglected pile on the edge of Hampstead Heath, in Highgate, is in the process of being sold for about £16million.

In October, previous owner, Athlone House Limited, lost a High Court battle to demolish the mock-Elizabethan building and replace it with a £80million eight-bedroom palace, with basement car park.

Campaigners branded it a “David versus Goliath” victory – and they say the underdog has won again this week, now that the former owner has abandoned the controversial plans for good.

Not much is yet known about the new owners, but Highgate Society vice-president, Michael Hammerson was told they want to restore the mansion to its former glory and only make minor amendments to the building.

“We were very relieved to hear of this latest development, and it shows that David can still slay Goliath when it comes to the planning system,” said Mr Hammerson, who has led the campaign to save the house from demolition.

“The new owners have shown us some preliminary details, which they were looking into before they bought it, for work to restore the house. They want to build a conservatory where an old conservatory was, which shouldn’t be hard at all.

“The most important thing is that they do not want a basement, apparently.”

Mr Hammerson said he knows the identity of the new owners, but is reluctant to divulge the name until he hears that the deal has definitely gone through.

The news comes after what Mr Hammerson described as a “long and hard-fought battle” to save the 19th-century building.

The battle started in earnest in 2004, when a former owner, under the same name of Athlone House Limited, was granted permission to build flats, known as Caenwood Court, in the grounds of the mansion – on the condition that the developer restored the former RAF intelligence base.

But the house was sold the following year to the most recent owners, who first bid to demolish the house in 2009.

That application was rejected on appeal in 2011, but just a year later, the fight began again when new demolition plans were unveiled.

More than 5,000 people, including Monty Python legend Terry Gilliam, backed the campaign to save it. The fight only came to an end in October with the High Court ruling.