Eh?
British courts consistently find that the 'public interest' defence outweighs any right to private property. In the scenario set out in the OP, the WBTS have to demonstrate that someone has harmed them financially to claim damages. If one shares freely and to inform against a cult, then I'm wondering what possible harm/damage they will be claiming to have been done. thegirlnextdoor makes one argument in her post, and if that's the best available, then the WBTS would be arguing in favour of the public interest defence :D