From bbc.co.uk Politics 09/09/2019:
Commons Speaker John Bercow to stand down.
Mr Bercow warned that if the appointment of his own successor was left until after the next election, newly-elected MPs might find themselves being “unduly influenced” by party whips in their choice of figure.
“It will mean a ballot is held when all members have some knowledge of the candidates. This is far preferable to a contest at the start of a Parliament where new MPs will not be similarly informed,” he told the Commons of his plans.
“We would not want anyone to be whipped senseless, would we?”
Image from Trillium Party of Ontario the only political party that does not, and will not, have a Party Whip.