Inheritance tax remains one of the most unpopular taxes and is loathed across the party lines.

A new YouGov poll for the Red Box found 59 per cent of voters thought inheritance tax was unfair – the highest figure for all the taxes polled. The BBC licence fee and fuel duty came joint second for the most unfair taxes while stamp duty came third at 48 per cent.

The Tories have long promised to cut inheritance tax but have failed to do so in this parliament. Labour has consistently attacked the Conservatives for making cuts to inheritance tax a political priority.

However, according to the YouGov poll, even Labour voters think the tax is unfair. It's widely expected the Tories will include a promise to raise the inheritance tax threshold to £1m.

Inheritance tax has become an increasingly salient issue with the electorate as the number of households vulnerable to the tax is set to soar over the next five years thanks to rising house prices.

The Tory pledge to raise the threshold was made at the Conservative party conference in 2007 and was widely credited with saving the party from an election they were likely to lose in 2010.

As if the nation's smokers hadn't had enough bad news, with the passage of plain cigarette packaging, 70 per cent of the public see taxes on tobacco as fair compared with only 17 per cent who think it's unfair.