Dealing with speculative invoicing

Here's a useful resource for those trying to deal with the menace of speculative invoicing: the Speculative Invoicing Handbook, second edition, produced by consumer group, Being Threatened. If it's got to a second edition without my becoming aware of it, I must be out of touch. It tells you how to deal with a situation in which you have received a letter from a law firm - oh, you know the guy, can't remember his name (well, I can, but I'm not going to write it here) - threatening you with all sorts of consequences for infringing copyright in something you have never heard of ... a pornographic film, for example. It could be useful for dealing with those photo agencies, too ...