Ms Lemon -

It's easy, but only for those registered and logged in, and only if they were logged in when they posted to the thread. I don't believe guests have a personal page.(?)

IFF they've added a name to the GUEST, e.g. "GUEST,Jethro" they can find all the posts using that name, so if they use a distinctive name they can search for prior uses of that specific one.

John