From King Constantine II of Greece and Saudi Arabia’s Sheikh Yamani to Russian billionaire Roman Abramovich, London’s mansions and penthouses have been a preferred haven for superrich exiles and expats since at least the 1970s.

Vladimir Putin’s invasion of Ukraine, and the subsequent targeting of Russia’s overseas money, threatens to end the British capital’s near 50-year run as the plutocrat’s playground of choice.

While plenty will welcome the possible demise of "Londongrad” — the soubriquet attached to the U.K. capital because of all the Russian cash swilling around its housing market — the city’s real estate firms are less thrilled about a broader clampdown on secretive foreign capital.