John Bercow has been found guilty of bullying House of Commons staff by the standards watchdog and banned from holding a pass allowing him access to parliament buildings for life.

A report published by the Independent Expert Panel into the former Commons speaker’s conduct states Mr Bercow “has been a serial liar” and “a serial bully”.

It adds that his behaviour “fell very far below that which public has a right to expect from any member of parliament” and that were he still a sitting MP, it would have been recommended that “he should be expelled by resolution of the House”.

“As it is, we recommend that he should never be permitted a pass to the parliamentary estate,” the report concludes.

In a statement released at the same time as the panel’s findings were published, Mr Bercow accused the investigation into allegations he acted improperly towards staff during his time as Commons speaker as “a protracted, amateurish and unjust process”.

Denouncing the report as “a travesty of justice”, the former speaker added: “Parliament is supposed to be the highest court in the land.

“This inquiry, which lasted a ghastly 22 months at great cost to the taxpayer, has failed it dismally.

“At the end of it, the panel has simply said that I should be denied a parliamentary pass which I have never applied for and do not want. That is the absurdity of its position.

“Don’t fall for the establishment spin that I have been banned for life. I can still attend debates with the help of a friendly passholder or go as a member of the public.”

The Independent Expert Panel, which determines sanctions in cases where bullying complaints have been brought against MPs, upheld the findings of Parliamentary Commissioner for Standards Kathryn Stone.

The panel rejected appeals by Mr Bercow over bullying against three people – Lord Lisvane, the former Commons clerk, Angus Sinclair and Kate Emms – and accused him of an “abuse of power”.

The parliamentary commissioner for standards had upheld 21 allegations against Mr Bercow across the three complainants, relating to the period 2009 to 2014.

The Independent Expert Panel concluded that the bullying and harassment policy “was breached repeatedly and extensively by the most senior member of the House of Commons”.

Its report continued: “It is for historians to judge whether the respondent was a successful reforming speaker of the House of Commons.

“However, there was no need to act as a bully in order to achieve that aim. A great office can be filled forcefully and effectively without descending to such behaviour.”

Former Conservative MP Mr Bercow stood down as speaker in 2019 and controversially defected to the Labour Party last year.

He was the longest-serving speaker since Edward FitzRoy, who served nearly 15 years in post between 1928 and 1943.

He presided over numerous Brexit rows in the Commons and, upon his departure, became the first speaker not to be offered a peerage in over 200 years.

Former Labour leader Jeremy Corbyn then nominated Mr Bercow for a peerage, but this was blocked due to the investigation into alleged wrongdoing.

Mr Bercow has repeatedly denied the allegations against him, previously claiming: “I have never bullied anyone, anywhere at any time in any way.”

In his statement on Tuesday, the former speaker continued: “All I can say is that the case against me would have been thrown out by any court in the land since it is based on the flimsiest of evidence, rooted in hearsay and baseless rumour, and advanced by old school dogmatists once intent on resisting change at all costs and now settling some ancient scores with me.

“Add to that a dash of personal spite and you have some idea of the vengeful vendetta mounted against me. It is a travesty of justice and brings shame on the House of Commons.

“This has been a protracted, amateurish and unjust process which would not have survived five minutes’ scrutiny in court.

“To describe what I have experienced as a kangaroo court is grossly insulting to kangaroos. None of the investigators is a lawyer and the Commissioner overseeing them has no expertise whatsoever in the consideration of alleged bullying.”

Mr Bercow also accused Ms Stone of hiding behind parliamentary privilege to “duck scrutiny and legal challenge”.

In a statement, Ms Stone said: “I am grateful to the Independent Expert Panel for their detailed and considered report regarding the conduct of Mr Bercow.

“Their report upholding my findings demonstrates my ongoing commitment to ensuring that the investigations under my oversight, and my subsequent decisions, are independent, impartial, thorough and fair.”

Meanwhile Dave Penman, general secretary of the FDA union which represents senior civil servants, said bullying had “flourished unchallenged” under Mr Bercow.