Chancellor George Osborne is expected to use Wednesday's Budget to deliver the party's promise to end inheritance tax on family homes worth up to £1 million.

It is understood that Mr Osborne is preparing to confirm that a new allowance enabling parents to pass on the main family home to their children tax-free after their death will come into effect from April 2017.

The pledge effectively to take all but the most expensive homes out of inheritance tax - at an estimated £1 billion cost to the Exchequer - was a key plank of the Conservatives' general election manifesto.

David Cameron said at the time that the party was responding to the "most basic, human and natural instinct there is" for parents to be able to pass on something to their children.

Mr Osborne and Mr Cameron had first promised to cut inheritance tax in 2007 - a move which was widely credited with deterring Gordon Brown from calling a snap general election he had been expected to win.

However, following the 2010 general election, the scheme was blocked by their Liberal Democrat coalition partners.

At the time of last May's election, the Tories estimated by 2020 22,000 families could benefit from the proposed new £175,000 main residence allowance. In a newspaper article, Mr Cameron and Mr Osborne said it was right the money should go to the offspring, and "not the taxman."