I'm afraid it comes under the "all too difficult" heading at the CAA. I expect they have a pretty good idea who is doing this but realistically it is very hard to obtain sufficient proof to get a conviction. If they ramp-check an aircraft at a race meeting they can't detain passengers or question them and the pilot will simply say no money changed hands so it's a private flight. Who'se to say different?
Even in a case as high-profile as this the complex paper-trail of ownership seems to hve been extremely difficult to follow and if all the protagonists deny any knowledge or say it wasn't me, someone else organised it prosecution seems agonisingly slow and difficult.