Evening Standard/London

A London mansion where John F Kennedy once lived is set to become the capital’s most expensive home, with an estimated price tag approaching £300mn.
The stucco-fronted property on Prince’s Gate in Knightsbridge, which was once the US ambassador’s residence, is being turned into a huge home by developers.
It quietly changed hands for around £70mn last week and is believed to have been snapped up by a billionaire Saudi family.
Plans lodged with Westminster council show that the row of Georgian townhouses opposite Hyde Park has planning permission to be turned into 41,000sq ft of opulent living space, providing “absolute security and privacy”.
This could be configured as two homes of 30,000sq ft and 11,000sq ft, or one vast mega-mansion about 30 times the size of a typical three-bedroom house.
Agents said the rich history of the houses, and their location a few hundred yards from One Hyde Park, could mean they fetch up to £7,000 a square foot.
If they were turned into a single home that would give them a price tag of £287mn, twice the current record confirmed in London, a £140mn penthouse at One Hyde Park.
Becky Fatemi, managing director of West End estate agent Rokstone, said: “The mansion is Grade II-listed, and could be configured as either one mega-mansion, or as two residences.
The property directly overlooks Hyde Park and it has the benefit of private gardens and terraces. The main staircase and the state rooms on the ground and first floor are extremely grand, and plans allow for the creation of a vast leisure complex on the lower ground floor.
“This is prime Knightsbridge, so if the property was refurbished and converted into a single super-prime mansion it could be worth anything from £200mn up to £290mn which, at the upper valuation, would make it London’s most expensive private home.”
The houses were sold to developers Viridis Properties 2 for £36mn in 2010. The company is registered in the British Virgin Islands but owned by Saudi-based Viridis Real Estate, the property investment arm of the Jameel family.
Plans submitted to Westminster council show a huge double basement which includes a leisure complex and underground car park, works estimated to cost £30mn.
The lower ground floor will have a swimming pool, children’s pool, Jacuzzi, kitchen, wine cellar, staff quarters and a gym with two changing rooms. Beneath it will be underground parking for four cars.
The ground floor will include a formal room and dining room, an ambassadorial study and a huge lobby. Cars will be driven into a separate entrance before being lowered to the basement via a large lift. The first floor has two large rooms for entertaining and a super-sized reception room stretches across the entire front of the property.
Upstairs are seven bedroom suites, another kitchen, a playroom and guest sitting-room. All floors can be reached by stairs or the lift. The property was built in the late 1840s to designs by the architect Harvey Lonsdale Elmes. It was the residence of Junius Spencer Morgan, the founder of the Morgan investment banking dynasty, and his son, John Pierpont Morgan, who offered the house to the US government.
John F Kennedy lived there in the late Thirties when his father Joseph was the ambassador to London and it was sold to the Independent Television Authority in 1955 and has been offices since.
More recently, it was the headquarters of the Royal College of General Practitioners. It was evacuated and taken over by the SAS during the Iranian embassy siege next door at 16 Prince’s Gate in April 1980.