The proportion of English and Welsh homes selling for over £1m has more than doubled during the Great Recession, in the latest evidence of the property market boom.
In London a record 7% of all home sales listed by the Land Registry in the year to March were for £1m or more - a sharp increase from the 3% level when Britain slid into recession in 2008.
Overall, the number of homes sold for £1m or more over the past year has surpassed 10,000 for the first time - with just over 11,000 £1m sales in the year to March.
This compares to around 9,000 at the peak of the pre-crisis boom.
Sky News analysis has also uncovered the affordability gap between different local authorities has reached unprecedented levels, driven up by a combination of high house prices and falling real wages.