To have any measure of influence we have to show we're willing to not vote Labour. This is arguably the best chance considering this is NOT FPTP assuming y'all are London brehs.
We don't have various well financed pressure groups like the jews have so our voice and interests will always be an afterthought.
That and it's one way to show our lack of confidence in the Labour leadership.
Andy Burnham would be a better leader, but people, let alone politicians rarely change. He'll always be a flip flopping soft left centrist.