Labour's planned mansion tax could hit as many as a quarter of all homes in Kensington and Chelsea.

Ed Balls, the shadow chancellor, announced yesterday at the Labour Party Conference in Manchester he wants to slap an annual levy on all properties worth over £2 million he says will raise £1.2 billion a year to be spent on the NHS.

The tax was initially a Lib Dem plan and has been around since 2009.

House sales since 2010 show 25.7 per cent, or 2,341, of all homes sold for £2m or more in England and Wales are in Kensington and Chelsea.

Westminster is close behind, with 1,725 homes sold for £2m or higher since 2010, making up 18.9 per cent of all £2m plus homes.

Kensington and Chelsea is also home to the country’s most expensive home sold since at least 2010, with a £54.96m home sold in The Boltons in 2012.

Around Westminster's Hyde Park it is almost impossible to find a house lower than £2 million

Chelsea and Fulham MP Greg Hands, said: “I think the Labour and Lib Dems mansion tax should be more properly called a home tax as in Hammersmith and Fulham and Kensington and Chelsea it will be almost all the terraced houses and many flats which will be hammered by the tax, regardless of ability to pay. There are lots of people who bought decades ago whose houses are worth over £2 million now but will not be able to pay.

“This is a tax on London and needs to be resisted very strongly.”

Paul Dimoldenberg, opposition Labour leader at Westminster Council, defended the tax saying it was not fair overseas billionaires who have bought in the past few years pay only £1,000 a year.

“The detail is the key - it’s important residents living in Westminster who bought their homes when they were young at a much lower price are protected."

He said Mr Balls made it clear those with more expensive homes would pay more while those closer to the £2m threshold would pay less.

After London, Greater Manchester has the second highest number of £2m homes - but there are only 36

Labour Party leader Ed Miliband dismissed using council tax to decide which homes would pass the threshold - an alternative estate agents have suggested would be fairer.

Hammersmith and Fulham had the fourth highest amount of £2m plus homes sold since 2010, with 444, and Camden comes in third with 672 homes.

In 2013 there were 2534 homes sold for £2m or more in England and Wales. According to the latest data there have been 1591 in 2014 so far - already eclipsing the entire number sold at or above that threshold in 2010.