Now a former clerk and a former official have branded him the “poison dwarf” at the top of the system.
According to reports the two junior members of staff complained in 2014 that Mr Bercow had shouted at them.
He is said to have later apologised.
The former clerk described how the Speaker’s former private secretary Kate Emms would be “distraught” and feared delivering messages in the Commons chamber in case the Speaker saw her.
He said: “We’ve lost some good people from the House of Commons and my guess is there’s some good people who haven’t joined us because of this.”
The other official, who reportedly worked 14-hour days for Mr Bercow, said: “He was a reasonable mimic and he would imitate me in front of other people, using words I never use, so that was very cruel.”
The official also claimed he was once recalled from holiday only to be told by the Speaker that he was not needed.
There were also allegations that Mr Bercow would blank staff, “making it difficult to work”.
And another complained that the Speaker would refuse to read research given him before meetings and then complain he had not been briefed.
“It was like dealing with a child,” the former official said.
“There was no reward, no interest and no help.”
A representative of the Speaker said: “The Speaker completely and utterly rejects the allegation that he behaved in such a manner.
Any suggestion to the contrary is simply untrue.”