Pressure on John Bercow over allegations of bullying in Westminster increased on Tuesday as three Tory MPs quit a Commons committee chaired by the Speaker.

Education minister Anne Milton, Welsh Office minister Mims Davies and Will Quince, a parliamentary aide to Defence Secretary Gavin Williamson, have stepped down from the reference group on representation and inclusion.

The aim of the committee is to ensure parliament is “truly representative, transparent, accessible, accountable and effective in all its functions”. It was set up by Bercow in 2016.

Quince told The Daily Telegraph he “cannot, in good conscience, remain as a member of the group while John Bercow is chair”.

He added: “As much as I personally like John, I have reluctantly reached the conclusion that he is not the right person to resolve the numerous and serious issues raised.”

It came after dozens of serving and former clerks and other officials – along with several MPs – yesterday called in a letter for the recommendations of an inquiry into Westminster’s bullying culture to be adopted in full.

The House of Commons Commission will meet tomorrow to decide whether to back the plan proposed by Dame Laura Cox.

Maria Miller told HuffPost UK she would also “consider her position” on the group if the Commons Commission did not adopt the recommendations in full.

MPs, including Miller, have called for Bercow to resign as Speaker following claims – which he denies – that he bullied two former officials.

The Speaker’s office said: “Dame Laura Cox’s report has highlighted some of the most significant challenges women face in our parliamentary culture.

“In the spirit of an independent approach, the Speaker feels it is right to reflect on the best means of tackling these cultural issues via the House’s response to the Cox report.

“He will therefore consider the future of the reference group following the commission meeting tomorrow.”

One former Commons staffer told HuffPost UK the Speaker called her a “little girl” because he was unable to find an envelope he was looking for. 

A spokesperson for Bercow said the Speaker had “absolutely no recollection” of the alleged incident.

David Natzler, the clerk of the House of Commons, told MPs on Tuesday there had always been a “subculture of bullying and harassment” in parliament.