Why do some topics show a paper clip in the 'list of topics'?

Bob

...err...don't rightly know...never thought about that...possibly it means there's an attachment or two in the replies...(like some of them have pictures in - my email does that when there's an attachment) I'm just guessing though...

Yep thats it exactly, it simply denotes that the message has an attachment, either a photograph or a file.

Regards
Eddy