Hugh manetee
People who want to join a union but don't want to contribute to the Labour Party just opt out.
Actually only 15 unions are affiliated to the Labour Party, although they include the largest unions.
Btw not opting into the political fund will also stop the union funding all sorts of other campaigns eg against NHS privatisation or sure start closures, or for the living wage, or to campaign in the EU referendum. The aim (or if not the aim, then certainly the result) is to shut off political voices.
I do get the point about wanting to support other political parties/objectives. But that's what the opt out is for.
fundamentally, the Labour Party is supposed to be a party funded by working people - unless they opt out. The clue is in the name. The opt out mechanism works because labour's funding is made up of thousands of tiny donations from workers, funnelled through unions (sorry, "barons"), while conservative funding is made up of funding from corporates and wealthy individuals.
A partial answer is for a cap on individual donations and employer/shareholder approval of corporate donations. However with a majority (even though tiny), right now the conservatives can force this through. Effectively this is a one in a generation opportunity for them.
This is why they are doing it early - while they still have at least a majority of 12 - and capitalising on the disorientation of labour.
However it raises very serious - indeed generation defining - issues of political legitimacy.