It is described by constitutional experts as the "nuclear" option. Ministers are considering asking the Queen to bring Parliament to an early close after the Speaker threatened to block the Prime Minister from holding a vote on her Brexit deal.

In an intervention that will cement his reputation as one of the most controversial Speakers in history, John Bercow said on Monday he would not allow Mrs May to put her deal to a vote for a third time unless it is "substantially" different - citing a convention that dates back to 1604 and was last used in 1920.

Downing Street was given no forewarning of the announcement, which threw the Government into chaos. The immediate impact was to kill the already receding hope ministers had that the third meaningful vote, known as MV3, could take place this week.

Ministers are now concentrating their efforts on finding ways around the latest "obstacle" that Mr Bercow has placed in their way while simultaneously trying to win round the DUP, Eurosceptic Tories and Labour rebels.