The developer confirmed today that it has already exchanged on 18 flats at the site at an average price of £4,750 per sq ft.

The 18 apartments will cost buyers £210m at an average price of £11.67m.

British Land said: “This pre-launch was limited and targeted at an exclusive list of known potential buyers and has been very well received.”

Laing O’Rourke started work on the Clarges Mayfair site earlier this year and the job is due for completion in 2017.

The residential-led scheme will contain 34 apartments over ten floors alongside 47,800 sq ft of high quality prime office space and 14,800 sq ft of retail and leisure space.

The total construction cost of the scheme will be £228m and the site cost British Land £130m to acquire.

The firm said: “Full marketing of the remaining units will be undertaken closer to completion when purchasers can appreciate the unique design of the building, its location and the panoramic views from the upper floors.”

Chris Grigg, CEO of British Land, said: “Clarges Mayfair is a great example of what we do well – investing in the right places and creating environments where people prefer to live and work.

“We have used our core development skills to increase significantly the value of the scheme creating a landmark building for this important area of London and further enhancing our presence in the West End.”