Senior figures who worked closely with Speaker John Bercow and accused him of bullying say there has been an “establishment stitch-up” in failing to investigate the outgoing chair.
Mr Bercow is set to step down from his role as House of Commons referee on Thursday.
Former Black Rod David Leakey and ex-private secretary Angus Sinclair have reportedly accused the powers-that-be of dragging their heels over acting on complaints against him.
It was announced last week the parliamentary authorities were opening the Independent Complaints and Grievance Scheme to former staff and would hear allegations dating back to before 2017.
The development comes more than a year after a report by Dame Laura Cox, a former High Court judge, warned of “deference and silence” being used to cover up misconduct occurring in Westminster.
But Mr Sinclair, who broke a non-disclosure agreement to speak out about alleged bullying by Mr Bercow last year, told a national newspaper the “horse has long bolted” in terms of probing the Speaker’s behaviour.
The 60-year-old has accused the former Tory MP of mimicking him and said he was prone to “over-the-top anger”.
He said the inaction regarding the bullying allegations was proof that “as yet the House of Commons is not a safe place”.
“The last year has shown me that when [the Commons] feels it’s got more important things to do, that sort of thing [bullying] doesn’t matter,” said Mr Sinclair, who was in the Royal Navy for 30 years.
Mr Leakey, 67, last year described an incident where the “red mist descended” on Mr Bercow, who he said “banged the table, yelled and was highly insulting to me personally”.
The former lieutenant general in the Army said Mr Bercow should be denied the usual peerage bestowed upon former Commons speakers.
“The icing on the cake of an establishment stitch-up in the public perception would be for Mr Bercow to be given a peerage,” warned Mr Leakey, who was one of the most senior officials in the Lords from 2011 to 2017.
“It would be a scandal that Parliament would struggle to live down.”
A spokesman for Mr Bercow insisted there was “no substance” to the allegations by either man and he has always denied claims that he has bullied staff.
A new speaker is due to be elected by MPs on 4 November.