David Cameron stands to avoid up to £80,000 in inheritance tax after his mother gave him £200,000 following the death of his father, it emerged on Saturday, as the Prime Minister took the unprecedented step of publishing details of his tax returns.

Under current tax rules, Mr Cameron would be able to legitimately avoid paying inheritance tax, which could be as much as 40 per cent, if his 82-year-old mother Mary lives for another two years.

The approach is commonly used by tens of thousands of families a year to help reduce their tax liabilities by using a “lifetime gift”. However, a Downing Street source was unable to say whether the money from Mrs Cameron came from his father’s offshore investments.