A ringleader of the rebels visited Speaker John Bercow, right, on Tuesday

Theresa May has been warned that her government “will lose its ability to govern” after Downing Street uncovered a bombshell plot by senior MPs to seize control of Brexit negotiations and sideline the prime minister.

A cross-party group of senior backbenchers — including former Tory ministers — plan what one senior figure branded a “very British coup” if May loses the crunch vote on her Brexit deal on Tuesday.

At least two groups of rebel MPs are plotting to change Commons rules so motions proposed by backbenchers take precedence over government business, upending the centuries-old relationship between executive and legislature.

Dominic Grieve: rebel ringleader BEN STANSALL/AFP/GETTY IMAGES

Downing Street believes that would enable MPs to suspend article 50, putting Brexit on hold, and could even lead to the referendum result being overturned