London's most expensive home: the Mayfair mega-mansion has the biggest asking price seen since lockdown

A lavish refurb includes a vast basement connecting the main mansion to the separate mews house behind. 
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One of the oldest mansions in Mayfair is up for sale for £54.5 million making it the most expensive property to come on the open market in London since lockdown.

The price tag for the Grade II listed 12-bedroom townhouse on Upper Grosvenor Street is more than 32 times higher than the £1.7 million it changed hands for in 2008.

The once near-derelict building between Park Lane and the former US embassy has been the subject of a lavish refurbishment ordered by the current owners, named at the Land Registry as Jersey-registered company Boss Holdings Ltd.

The overhaul, overseen by Camden-based architects The Kalyvides Partnership, has created a vast residence of 14,500 sq ft that includes a mews house connected by a huge basement and the ground floor.

The subterranean level includes a 73 ft long swimming pool thought to be one the biggest in a private home in central London, jacuzzi, fitness studio, sauna and “home theatre” as well as staff quarters.

The six storey house, fronted in Portland Stone, was originally built in 1732 when the streets and squares of Mayfair were first being laid out.

It was modernised in the “Edwardian Baroque” style in 1908 by architect Ralph Nott, who is best known as the designer of County Hall, the home of the former Greater London Council. The mews house behind in Culross Street dates to 1869.

Agents say they have seen a huge surge in demand for larger properties with outdoor space and room for home working since the start of the pandemic.

'Enviable spa': the house has a separate spa pool (above) in addition to one of Mayfair's largest private swimming pools

Latest figures this week from agents Savills revealed that a total of 226 homes with a price tag more £5 million changed hands in London in the first nine months of 2020, a 12 per cent rise on last year.

Rob Windsor, director of agents Clifton Property Partners, along with Knight Frank, said the house, which had been previously been let and was advertised with a rent of £27,500 a week, said it had been in poor condition when the current owners bought it six years ago.

He said: “You could stand on the ground floor and look all the way to the top through the rotten floorboards. Now it really is the whole package, large freehold house, mews and lots of outdor space.”

He added: “Mayfair houses offering impressive period grandeur, self-contained leisure facilities, extensive private gardens and interconnecting mews accommodation are exceptionally rare, so perhaps unsurprisingly, we’ve seen strong interest from both domestic and overseas buyers mindful of the quality and scarcity of houses such as Upper Grosvenor Street.

“The immediate vicinity is presently undergoing an astonishing transformation with the Rosewood Hotel soon to open its doors on Grosvenor Square, and the Square itself also set to be radically improved and enhanced, surely positioning Upper Grosvenor Street as one of the most sought after addresses in London.”