DOWNING St has intervened over the fresh claims of bullying against John Bercow, saying they are very concerning and must be “investigated thoroughly”.

Lord Lisvane, the former Clerk of the Commons, is said to have handed a dossier of allegations against the ex-Speaker to the Parliamentary Commissioner for Standards.

Mr Bercow has denied all allegations of bullying and described the timing of the peer’s complaint as “curious”.

It comes as it is also suggested that Jeremy Corbyn has nominated the former Speaker for a peerage in the forthcoming Dissolution Honours List. Traditonally, ex-Speakers are nominated for a peerage by the sitting Government.

Andrea Leadsom, the Business Secretary, who clashed on a number of occasions in the Commons chamber with Mr Bercow, said if the complaint of bullying were upheld, then it should have an "impact" on whether he was made a peer.

"The whole purpose of that was that anybody, including the Speaker of the House of Commons whoever he or she may be, should also be subject to that procedure," she told Sky News.

"In the event that there are genuine, upheld complaints about any persons that should have an impact on whether they are found suitable for the House of Lords," added Ms Leadsom.

It is suggested Lord Lisvane’s complaint alleges incidents in which Mr Bercow was said to have bullied and humiliated staff with, in some instances, the use of inappropriate language.

Asked about the bullying claims allegations against Mr Bercow, Boris Johnson’s spokesman said: “These are very concerning allegations and they need to be investigated thoroughly.

"Everyone working in Parliament deserves to be treated with dignity and respect. There can be no place for bullying or abuse in Westminster or any workplace and it is important that the parliamentary leadership responds fully and promptly to any concerns which are raised."

Commenting on Lord Lisvane’s claims, Mr Bercow, who has consistently denied allegations of bullying during his time in the Chair, hit back, "categorically" denying having ever bullied anyone and criticising Lord Lisvane.

In a statement, he said that since retiring it had "become increasingly obvious that the Government has no intention of honouring the centuries-old convention that a departing Speaker is promptly elevated to the House of Lords".

He continued: "Indeed, it has been suggested to me that the Government actively seeks to block any other attempt to nominate me for membership of the upper House.

"I have seen in the media that Lord Lisvane is formally complaining that I bullied staff. For the record, I categorically deny that I have ever bullied anyone, anywhere at any time."

The former Speaker said the peer had "ample opportunity to raise any concerns about such conduct with me" and had "a duty of care to all House staff".

Mr Bercow stressed: "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," he added. 

The former Speaker had earlier described the timing of Lord Lisvane's complaint as "curious".

All nominees for peerages are vetted by the House of Lords Appointments Commission, which must consider whether past conduct could be regarded as bringing the upper chamber into disrepute.