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

Senior Tory MPs blocked moves to give Commons researchers and secretaries extra protection from sexual harassment, it can be revealed today.

The powerful 1922 Committee of backbenchers mobilised against an attempt made by David Cameron to create a binding code of conduct that would have included a right for staff members to seek arbitration.

Mr Cameron attempted to persuade the Speaker and other party leaders to support the measures following a sex scandal but his move met resistance from MPs, said sources.

The former Prime Minister then attempted to get his own MPs to sign up voluntarily.

But this was blocked by the 1922 Committee, which saw the plan as a whips’ plot to impose “central control” on backbenchers. As the Westminster “sex pest” furore deepened:

Downing Street failed to give full confidence to international trade minister Mark Garnier, who admits getting his secretary to buy sex toys in Soho on his behalf. No 10 said it would not pre-empt an official Cabinet Office inquiry.

Caroline Edmondson, Mr Garnier’s former secretary, told the Standard that sexual harassment was “endemic” at Westminster.

Theresa May offered to hold talks with Speaker John Bercow on overhauling Commons disciplinary procedures to make all MPs offer legally binding grievance procedures.

A spreadsheet alleging 36 Conservative MPs — including 20 ministers — were guilty of inappropriate behaviour was drawn up by a secret group of secretaries and leaked.

In a letter to Mr Bercow, Mrs May said the current grievance system for dealing with complaints by MPs’ staff lacked “teeth” as there was no contractual requirement for MPs to follow the rules.

However, it now emerges that binding rules could have been in place three years ago but for the backbench opposition.

Mrs May was among Cabinet ministers who backed Mr Cameron’s bid to establish an independent system to oversee complaints.

The episode followed a scandal in 2014 when a Tory official, Iain Corby, was accused of sending messages that referred to “cute boys”, “orgy”, “gay party”, and “hottie MPs”.

He was in charge of the Parliamentary Research Unit, a Tory group that supplied information to MPs and their researchers.

Graham Brady, chairman of the 1922 Committee, confirmed that the organisation had opposed Mr Cameron’s subsequent attempt to get all Tories to sign up voluntarily. He said: “The point made was that this should be an issue for all political parties, not just one. Our view was that matters of that sort should be for the whole House of Commons, not one side.”

Mr Brady said there was unease that the Conservative whips would be in charge of the voluntary system, which opened up a potential conflict of interest if it was in the Government’s interests to get rid of an MP unfairly accused of misconduct. “It might not always be about achieving a fair and just outcome,” said Mr Brady.

Tory backbencher Anna Soubry said she backed Mrs May’s call for a new code of conduct but said it must cover all MPs and Parliamentary staff. She said: “What it must do of course is to protect all workers that are at the Palace of Westminster. At the moment it looks like it is only going to deal with those situations, where a member of your team wants to make a complaint against a member of Parliament.”

Ms Soubry said the current system in which MPs are personally liable if a grievance ends up at an employment tribunal is “completely wrong”. She said: “We need to sort out the whips.”

Tory ex-Cabinet minister Nicky Morgan said “a new system and culture” was needed to protect staff and urged Mrs May “to get a grip on this now”.

A Labour source said they changed procedures in 2014 to improve how claims of harassment, bullying and discrimination were dealt with.

He said: “The Conservatives have always been a lot more keen to do things on a House and cross-party basis because they struggle to get things through their 1922 Committee.”

Mrs May was also facing calls to suspend a second senior Conservative, former Cabinet minister Stephen Crabb, after he was reported to have admitted sending explicit messages to a 19-year-old woman he interviewed for a job.