Plans have been submitted to turn a series of properties in Mayfair into a £70m super home.
The mansion at Eight Grosvenor Square would come with an underground leisure complex and, at 190ft - more than half the size of a football pitch -could become the longest in London.
The 18th Century building, on the corner of Grosvenor Square, Mayfair, will stretch all the way back so it incorporates the mews homes on Duke’s Yard.
It will boast large entertaining rooms, underground leisure facilities, luxury sleeping quarters, a courtyard and a price-tag of around £70m.
Estate agents believe the latest potential “trophy home” will have no shortage of interest from wealthy foreigners buying up Mayfair.
It was originally built in the 1720s and used by the US army during the Second World War.
In 1965 it became the London office for Manufacturers Hanover Bank. The developer now wants to return it to a family home and integrate the mews properties at the rear, stretching the property around 190ft.
Plans suggest the proposed home, which could be around 18,000sq/ft, will boast six main bedrooms, a stunning drawing room, staff quarters and garaging for six cars.
Leisure facilities - which includes a gym, underground swimming pool, jacuzzi and a large cinema - will be at the rear.
'Grand' townhouse
The second floor will be arranged as an apartment for the owner, consisting of two enormous bedrooms with ensuite bathrooms and a large sitting room.
In the lower ground floor is a kitchen, pantry, a room for security, laundry and butler’s quarters.
The dining room alone is more than 800sq/ft in size - the same as the average new home in England.
Previous proposals for work on 8 Grosvenor Square have been approved, but fresh plans submitted to Westminster Council includes work on a new sub-basement, basement and ground floors.
If approved, the property could achieve as much as £4,000 per sq/ft, according to Becky Fatemi, managing director of Rokstone Estate Agency.
She said: “The grand Georgian townhouse was originally built in 1725, and is notable because it is an extremely deep property, that runs all the way out onto Duke’s Yard, effectively taking up almost an entire city block.
“I’ve not really come across another house which is as deep as 8 Grosvenor Square - it will be a real trophy home.
“Grand townhouses in and around Grosvenor Square typically sell for around £3,000 per sq/ft, but by the time work is carried out they could be achieving £4,000 per sq/ft.
“There is always demand for house like this in Mayfair because they are few and far between. They tend to be popular with wealthy Middle Eastern, Indian and African buyers.
“I have just come off the phone with a client who is looking for a 10,000sq/ft property and has a budget of more than £50m.”
