Bercow is an unelected preening self publicist
Problem with Bercow (for those that want to go on about one convention) is that he has broken many other conventions.
He has politicised the role of the speaker which will be a fundamental change in the role of the Speaker going forward.
As speaker should not have declared his remain vote.
I will claim a bias here. I was at university with him and he was an obnoxious prat. As right wing as you can get (neo nazi past well documented) and an attention seeker. Loved to needle people for the sake of it. Anyone who knows university politics will tell Essex was not the place for Tory politics!!
Entered Parliament on the right wing of the Conservative party and noted eurosceptic. His swing to the left following his marriage sums up his convenience politics.