ES News email The latest headlines in your inbox twice a day Monday - Friday plus breaking news updates Enter your email address Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid You already have an account. Please log in Register with your social account or click here to log in I would like to receive lunchtime headlines Monday - Friday plus breaking news alerts, by email Update newsletter preferences

Ministers were plunged into a Brexit bullying row today as whips were accused of reducing a female MP to tears.

A male whip was alleged to have used “bully boy tactics” that left the MP trembling and crying in the Commons. It came as tensions soared ahead of a critical Brexit vote tonight where Theresa May is in danger of suffering her first major parliamentary defeat.

Tory former business minister Anna Soubry said the pressure on potential rebels to toe the line had gone too far.

She told the Standard that the MP was left in distress after a conversation with a whip who tried to make her vote with the Government.

Ms Soubry said: “It is right that the whips should exert pressure, cajole people — that’s perfectly proper in my view. But bullying, reducing colleagues to tears and making them shake is not acceptable. It has got to stop. We are the Conservative Party, not Momentum thugs.”

Two other MPs also said they were aware of the incident. One senior MP said: “The person was left shaken and upset. These were bully boy tactics.”

About two dozen potential Tory “mutineers” have threatened to support an amendment put down by former attorney general Dominic Grieve that would give Parliament, rather than the Government, the final say on any Brexit deal hammered out by Mrs May next year.

The numbers are enough to overturn the Prime Minister’s working majority of 12, even if some rebels abstain rather than vote for the amendment.

During last night’s debate on the issue, Tory whip Chris Heaton-Harris was observed talking to one of the potential rebels, who was said to have been upset afterwards. No 10 said it was “categorically not true” that he had caused the MP to cry or feel intimidated.

This year Mr Heaton-Harris denied trying to “intimidate” academics after he wrote to universities asking to know what staff were teaching about Brexit.

He told the Standard: “You will have to go through No 10 to get any comment from me.” The female MP did not respond to requests for a comment.

This morning Cabinet minister Justine Greening told Radio 4’s Today show: “We’re going to make sure that through the concessions today we continue to command the support of Parliament.”

Brexit Secretary David Davis wrote to all MPs in a last-ditch attempt to get support. He also issued a written statement spelling out in more detail the process for voting on a Brexit deal, which promised not to implement the deal until after MPs have voted.

Mr Grieve rejected this as failing to offer a meaningful vote. He urged MPs not to fall for “woolly concessions”. He is seeking a special Act of Parliament to enshrine the Brexit deal before it is too late for Parliament to seek changes.

Mrs May faces a potentially bigger rebellion when MPs vote, probably next week, on her attempt to fix into law the Brexit date of March 29, 2019.