The scrapping of the 'non-dom' tax regime has produced one set of beneficiaries: families wanting to move to London's poshest parts.

Areas such as Belgravia and Knightsbridge, with their white stucco terraces, are suddenly within reach of well-off families previously exiled as prices are slashed by up to 40 per cent.

Becky Fatemi of estate agent Sotheby's said: 'There has never been a better time to start looking in Kensington, Knightsbridge and Westminster – the areas non-doms have typically left.'

By contrast £1 million-plus properties in Chiswick and other more outlying areas need to be trimmed by just 5 per cent to sell.

About 10 per cent of non-domiciled residents have fled the UK, driven out by changes to inheritance tax among other shifts in the rules. Fatemi says a year ago some period Knightsbridge houses were changing hands at £2,500 a square foot. This has fallen 40 per cent to £1,500-£1,600. The average UK price is £300.

Period houses on three or more storeys and without a lift are languishing on the market, for those longing for Regency era Bridgerton-type elegance.

Overseas investors pay 19 per cent stamp duty on a second home amounting to a £4.6 million stamp duty bill on a £25,000,000 house. This falls to £2.9 million for a UK buyer who does not own another home.

However, Fatemi warns: 'There is only a four-to-five-month window of a good supply of homes because another influx of American prime central London househunters has started.'