The mysterious owner of Witanhurst - London’s largest private house - has finally been revealed to be one of Russia’s richest men.

Fertilizer magnate Andrew Guryev Sr has been named as the “beneficiary” of the sprawling mansion off Highgate West Hill for the first time following years of speculation about who owns the property.

The house’s status as the largest in London after Buckingham Palace will be cemented once extensive renovation works to build a £50million underground palace are complete.

Mr Guryev’s identity was revealed by The New Yorker on Sunday in an eight-page feature on the mansion and its current owner.

The 55-year-old, who is reported to be worth about £2.6billion, is the founder and deputy chairman of PhoAgro, one of the world’s largest fertilizer producers.

In a statement to The New Yorker, a spokesman for Mr Guryev said the Russian billionaire is not the “legal owner” of Witanhurst, but a beneficiary of the company that owns the property.

But the spokesman added that the house was always intended for the use of “the benefit of the family”.