In reply to andyhodges:
As a total random who read this out of curiosity, I'm fairly shocked if your post is true.
I'm no lawyer (though my better half is such a thing), but you should perhaps contact them and point out that they are damaging your ability to fundraise by lying about their association, that you have had to take steps to edit your website etc, and that you intend to seek to recoup any expenses required to combat their innacuracy through the courts, along with any apparent loss of income.
And then you should do exactly as you have threatened.
I don't say this to be hysterical, but because it is actually quite cheap and easy to make their lives difficult in this way. I would definitly find someone to give you some friendly legal advice first though.
Good posting though; it comes up on google when you look for the event...
Best,
Mark