Ministers have been warned that MPs supporting an amendment to delay Brexit could “politicise the monarchy” and lead to a “full blown constitutional crisis” causing the Government to “lose its ability to govern” according to leaked documents seen by the Telegraph.

The explosive memo advising the cabinet as Theresa May battles to win Tuesday’s second meaningful vote - warns that supporting any amendment re-tabled by Labour’s Yvette Cooper and Tories Oliver Letwin and Nick Boles could pave the way for a bill to change the day of our EU exit and bind the Government into a permanent customs union.

It comes as at least four Cabinet ministers are poised to vote to block no deal next week if Mrs May's withdrawal agreement is rejected, prompting the Prime Minister to consider offering Tory MPs a free vote on the matter to avoid a mass resignation. Philip Hammond, Amber Rudd, David Gauke and Greg Clark are all expected to rebel against the Government.

If Mrs May’s deal is voted down and there is no support for leaving the EU without a deal in parliament, MPs will then be given the option to vote to delay Brexit.