The combination of significantly lower prices for desireable London property and a strong U.S. dollar – both seen as at least in part as the result of uncertainty over Britain's political future as a result of the UK's Brexit troubles – has seen at least some wealthy Americans snapping up some of the most expensive of these London properties, at reduced prices that most people would still consider to be eye-watering.

Hong Kong saw the greatest number of sales of ultra-prime residences costing more than US$25m (£22.1m, £19.9m) in the year to the end of August, according to a first-ever assessment of this market by Knight Frank.

New York and London ranked in second and third place respectively, the London-based property company's research revealed.