The property consultants analysed sales data to see what type of “mansions” would fall into the £2m plus category Labour leader Ed Miliband would target if his party came to power.
Knight Frank said London – and in particular the prime areas of Westminster and Kensington & Chelsea – would be hit harder than other parts of the country by the tax. The two boroughs alone account for 46 per cent of the £2m-plus properties in England and Wales, and 26 per cent of properties eligible for the mansion tax in England and Wales are flats in those two areas.
Across Greater London, 38 per cent of all of the taxable properties are flats while only 14 per cent are detached. Terraced houses are the second-largest group falling into the category, at 36 per cent, while semi-detached properties make up the remaining 12 per cent.
“The figures demonstrate the mismatch between perception, in particular the term “mansion”, and the reality of the London property market, where three-quarters of £2m -plus properties are either flats or terraced houses,” said Tom Bill, of Knight Frank.
The real estate group said any further property tax would also come on top of the large and growing contribution London already makes in the form of stamp duty.
New data for the 2013/14 tax year shows London properties contributed 81 per cent of stamp duty revenue in the £2m-plus price bracket in England and Wales, up from 79 per cent in the previous year.
Miliband’s proposals have come under fire from economists and homeowners. Adam Smith Institute’s head of policy Ben Southwood dubbed the measures “bizarre” and former England footballer Sol Campbell said he might join the Conservatives.