It's not really in the spirit of this thread but I actually don't think the Westminster system would work very well with a 500+ seat Labour government.
Indeed, but you never know, it's wishful thinking but:-
500+ seat Labour Government
Push through PR
Have a practice election under PR to get people used to the idea
Call a real GE under PR
Come back with a lower majority and more of an opposition and a more representative opposition
If Starmer does that I would have huge respect for him, but I wouldn't fault him for waiting 4-5 years between steps 1 and 2 to execute his policy programme. First priority would be to reverse measures of the last 12 years that continue to cause real harm every day.
Indeed, but you never know, it's wishful thinking but:-