In contrast in Canada our version of the Labour Party - the NDP - is 100% pro-choice and you are not allowed to be a candidate (let alone sit in caucus) unless you pledge to support abortion rights in any parliamentary vote. The Liberals used to be more divided but now their leader Justin Trudeau has also said that no one will be allowed to run in the next election unless they support abortion rights - though a handful of incumbent pro-life Liberal MPs will be "grandfathered" and allowed to continue to be anti-choice.
The silver lining in this is that the NDP has never, and will never form government, so I guess they can do what they want.