Buyers of expensive properties likely to attract mansion tax are offering two prices – a Cameron price and a Miliband price.

The Cameron price, offered in the event of a Tory victory, is the higher. The Miliband price, offered in the event of Labour victory which would herald in the annual tax on owners of properties worth £2m plus, is the lower.

According to a report in yesterday’s Sunday Times, one buyer of a property just over £2m in Notting Hill, London, has told agents Strutt & Parker he will pay that price only if Cameron gets back in. Otherwise, he will pay 5% less to keep it below the threshold.

In another case, the buyer has bid £3.75m for a home but will increase his offer by £75,000 if there is a Conservative victory.

According to Ed Mead, of Douglas & Gordon in London, some sellers have offered to pay five years’ worth of mansion tax to cover the whole of a Labour term in office.

Labour plans to levy £3,000 a year on owners of properties worth between £2m and £3m, but charge more for pricier homes.

Marc Schneiderman, of Arlington Residential, said he has one buyer who wants to drop his offer for a £15m property by £1.5m if Labour wins.

Schneiderman told the Sunday Times: “He is not trying to take advantage.

“It is just his understanding of what will happen to the market if it is anything other than an outright Tory majority or a Tory-Lib Dem coalition.”

According to Rightmove, 77 homes originally on the market at over £2m have had their prices reduced to below that level in the past six weeks.

Ed Miliband lives in a London semi valued at £2.7m.