Why UK’s Makerfield by-election matters far beyond one parliamentary seat

The by-election in Makerfield, northwest England, takes place on Thursday. It was triggered after MP Josh Simons stood down to allow Manchester Mayor Andy Burnham to contest the seat. If Burnham wins, he plans to challenge Prime Minister Keir Starmer for the leadership of the Labour Party. Reform UK candidate Robert Kenyon, despite controversy over sexist posts, poses a real challenge in a seat Labour has held since 1983.