MPs should be barred from determining the outcome of bullying or sexual harassment claims made against their Commons colleagues, Westminster officials have said.

In an “unprecedented” letter, dozens of serving and former clerks and other officials – along with several MPs – called for the recommendations of an inquiry into Westminster’s bullying culture to be adopted in full.

The officials said that, as well as MPs being stripped of a role in determining allegations about colleagues, the complaints procedures should also be amended so historic claims can be investigated.

The letter comes after High Court judge Dame Laura Cox lifted the lid on a toxic environment in Westminster, which included staff having their bottoms and breasts touched in an atmosphere fuelled by ready access to alcohol.

Her report found that a culture of “deference, subservience, acquiescence and silence” had allowed the mistreatment of staff in the House of Commons to thrive.

The report heaped pressure on Commons Speaker John Bercow, who has himself been the subject of bullying allegations, which he denies.

In their letter to the ruling House of Commons Commission, the former officials said “we have personally experienced, or seen first-hand, bullying or harassment by Members of Parliament left to go unchallenged.

“Dame Laura Cox’s report has exposed Westminster’s open secret – a minority of parliamentarians have been allowed to get away with this behaviour for years.”

Dr Hannah White, a former senior clerk who signed the letter, said: “The significance of this letter should not be under-estimated – it’s deeply counter-cultural for House staff to speak out in this way – it demonstrates the depth of their frustration with MPs’ response to the Cox Report.

“It’s unprecedented for staff to speak out in this way – they are used to working invisibly to make the Commons function and help MPs do their jobs.

“But they see this as a matter of HR, not politics, and are writing to the commission to urge them to implement the report.”

John Bercow has faced calls following the report into Westminster's bullying culture (Rick Findler/PA)
John Bercow has faced calls to quit following the report into Westminster’s bullying culture (Rick Findler/PA)

The commission meets on Wednesday to discuss the Cox Report, with independent member Jane McCall chairing the panel rather than Mr Bercow.

Dr White, now director of research at the Institute for Government, said there is concern that the commission “may resist or delay implementing the recommendations of the Cox Report for personal or political reasons, instead of seizing the opportunity for reform”.

Mr Bercow has faced calls to quit following the publication of the report.

Tory former minister Maria Miller, who chairs the Women and Equalities Committee, told him: “The report is clear that there needs to be a complete change in leadership at the most senior level, including you, Mr Speaker, as chief officer, if we are, in Dame Laura’s words, to press the reset button.”