Well that's only the second time I've had to remove an *entire convention* from my photo gallery... not much I can do when they're happy to pay for a solicitor to send a legal threat. What a waste of attendees' money - they only needed to email and ask.
That's unfortunate. Outside of specific situations where a judge has granted a gag order, legal letters from an attorney in the US, at least as far as C&Ds go, can be freely posted no matter what threatening language they use to imply otherwise. Shame it's not so in the UK.