Once a meeting is called, a motion of no confidence in Johnson would be held. Although the result is non-binding, its symbolic power would be substantial, rebel MPs believe, and could offer ministers and even Cabinet ministers a reason to stage a wave of resignations. May survived a confidence vote by her MPs in December 2018, and under rules of the backbench 1922 Committee could not be challenged again for another year.
But grassroots activists successfully triggered an emergency meeting of the NCC for June 2019. Their petition at the time declared “we no longer feel that Mrs May is the right person to continue as Prime Minister” and planned to use their meeting to pass a motion to that effect.
In the end, the meeting never happened because May bowed to pressure to resign just a few weeks beforehand. As well as the prospect of a new challenge by MPs, the threat of the ignominy of such a damning verdict being passed by the “voluntary” wing of the Tory party was enough to force her hand.