Walk through the gilded streets of Belgravia, Knightsbridge and Mayfair, and it’s eerily quiet. That is, except for the sound of estate agents clicking their heels, waiting for the British economy to grind back into action.

Billionaires, multi-millionaires and even plain millionaires have been leaving the country in droves since the last election. That means that at the top end of the London housing market – ‘prime’ or ‘super-prime’ – there are far more houses and flats for sale than there are buyers.