Tory grandees are urging Boris Johnson to urgently introduce legal changes that could give the Prime Minister 20 more seats at the next election.

Two former Conservative chairmen, an ex constitution minister, and Sir Graham Brady, the head of the 1922 committee of backbenchers, are among senior party figures calling on the Prime Minister to change the "deeply-flawed" parliamentary constituency boundaries "as fast as possible".

Last week an analysis revealed that the Conservatives would have a 104-seat majority under proposed changes put forward by the Boundary Commissions in 2018 for a slimmed down 600-seat House of Commons.

The reforms were proposed under a process that sees the size and shape of parliamentary boundaries periodically reviewed in order to keep up with changes in population size.

The Conservatives' election manifesto included a pledge to "update and equal Parliamentary boundaries" to ensure that "every vote counts the same" - but last week's Queen's Speech, which set out Mr Johnson's legislative programme, contained no explicit reference to the changes, which were shelved under Mrs May because of her lack of the majority needed to gain the approval of the Commons.

In a letter to The Sunday Telegraph, six senior Conservatives, led by John Penrose, the former constitution minister, said it was "essential for the health and credibility" of Britain's democracy to introduce the changes "immediately" - meaning they would be in place for the next election.