Thanks for the reply Chris.
I will bookmark all that and see what I can do with the info/fixes suggested.
Yes I'm pretty sure it is human, judging by the lame attempts at the nics. You can see it is someone who has some idea of English without really getting the way English speakers put together nics for forums.
Yes, capatcha is on.
Yes, version 3 (this refers to phpbb3 I assume)
Pretty sure I'm not making them exceptions. The ACP says exceptions will be "emphasised". I'm assuming that means the text for exceptions will stand out in some way. All on the list look to be in the same standard text.
That idea of a custom field looks interesting. I could have some fun with that.
Since I set the registrations to user activitated they have stopped, but I anticipate that is short term cure which may have worse consequences if left like that for too long. I've already got a regular idiot(s) who post porn spam, abusing the guest facility set on pre-approval for a particular sub-forum.
Ok, I am on the scent now. Thanks for your help.