- Video report by ITV News Political Correspondent Paul Brand
A formal bullying complaint has been filed against former Commons speaker John Bercow by a peer who served as his most senior official.
Lord Lisvane, who was Clerk of the House, confirmed the complaint to ITV News, alleging staff were "bullied" and "humiliated" by Mr Bercow.
He has handed a dossier of allegations to the Parliamentary Commissioner for Standards.
Mr Bercow dismissed the claims as having come at a “curious” time, with suggestions that he may be in line for a peerage and said he "categorically" denied he had "ever bullied anyone, anywhere at any time".
The document is said to accuse Mr Bercow of having bullied and humiliated staff, including using inappropriate language.
Mr Bercow has consistently denied allegations of bullying from former members of staff in the past.
Former black rod David Leakey told ITV News Mr Bercow would "lose his temper," adding "he would descend into a fury of insults".
"He would attempt to bully, intimidate, and harass".
Mr Leakey, a former colleague of Mr Bercow, said it would be "totally absurd for anyone to think that he should be given a peerage".
In response to Mr Leakey's comments, a spokesperson for Mr Bercow said the former speaker "only met David Leakey three or four times a year, to discuss matters like seating arrangements when foreign dignitaries were making a speech".
When asked by ITV News asked Shadow Foreign Secretary Emily Thornberry if these allegations should disqualify Mr Bercow from a peerage, she defended Labour's decision to nominate him.
She said: "If everybody who had things alleged against them were not able... it was just assumed that it must be right, then what's the point in having a justice system?"
In 2018 former Leader of the House, Andrea Leadsom said claims of bullying were a “huge concern” and recommended a “short, independently led” inquiry.
It followed a BBC Two Newsnight report which alleged Mr Bercow had shouted and undermined his former private secretary Kate Emms, leading to her being signed off sick.
In a statement on Thursday, Mr Bercow said: "For the record, I categorically deny that I have ever bullied anyone, anywhere at any time."
Addressing Lord Lisvane's complaint in particular, Mr Bercow added that the pair had worked together for five years and during that time Lord Lisvane "had ample opportunity to raise any concerns about such conduct with me.
"Moreover, as Chief Executive of the Commons and Head of the House Service, he had a duty of care to all House staff.
"Therefore, he had not merely a right but a responsibility to act if he thought that he witnessed misconduct.
"The simple fact is that he did not at any time do so.
"Even though he frequently disagreed with me on a wide range of issues, he did not once complain to me and neither did any other official on his behalf."
Outgoing Labour leader Jeremy Corbyn has reportedly been lining up Mr Bercow, who was a Tory MP before becoming speaker, for a peerage.
The suggestion had been made after Mr Bercow became the first speaker in 2030 years not to be made a lord following conflict with the government over Brexit.
And there are suggestions Downing Street could hamper Mr Corbyn's bid to make Bercow a lord, with the Prime Minister’s official spokesman highlighting a “long-standing convention” that opposition leaders nominate individuals form their own parties.
Mr Bercow left the speaker’s chair on October 31 and has been replaced by Sir Lindsay Hoyle.