A Regent’s Park mansion known as “London’s White House” has been bought by an American tech billionaire in what could be the second-most expensive property deal in British history.

The unnamed buyer, one of an influx of rich US businessmen buying London homes in recent months, has spent £139 million on the Holme, negotiating a £111 million discount from its Saudi owner.

In purchases like these, super-rich buyers in London typically also base their “private offices” — or work premises — in their mansions, allowing them to pay a reduced rate of 5 per cent stamp duty, rather than a full residential rate for foreign buyers of 17 per cent, saving millions of pounds in tax. It is not known whether he did so in