The electoral commission has a list of donors to the parties standing in the Rother Valley, which you can read here.
Lynda Donaldson has tweeted about the Labour Party being funded by the unions (as though that were news):
Labour reliant on the trade unions, in 2009 the unions provided 60% of Labour’s funding, does your MP receive Union funding from UNITE??????
But at least we know who the Unions are, and what their agenda is. We can only speculate as to who the major donor to the Rother Valley campaign for the Conservative party is, what his motivation is, or what influence he has.