At first glance, Five Belgrave Square looks like a grand London mansion hastily abandoned by its aristocratic owner. Imposing white columns, paint peeling off them, line the entrance alongside a makeshift barrier of brown packing tape and imposing security doors. It is a ghostly symbol of old money, power and influence whose running costs exceeded its owner’s resources.

Now worth £50m, it is owned by Oleg Deripaska, one of President Putin’s favourite Russian oligarchs who has benefited from huge state-backed contracts and is a regular visitor to the Kremlin, according to leaked diplomatic cables published by Wikileaks.

Deripaska bought the house for £17m in 2003 using an offshore company registered in the British Virgin Islands. His ownership of this historic property – once home to Sir Henry “Chips” Channon (1897-1958), a Conservative MP with notoriously decadent tastes – is now frozen as part of the government’s sanctions against the oligarchs.

It’s worth being precise about what “frozen” means in this context. Putin’s war in Ukraine triggered the sanctions – but sanctions restrict use, they don’t transfer ownership. Deripaska, like every oligarch named in this investigation, is still the legal owner of his London property. He cannot sell it or live in it while sanctions apply, but he has not lost it, and the day sanctions are lifted, he is free to walk back through his own front door.