Cheers once again, Milo; I owe you a beer or ten.
Still struggling with it, but getting closer or at least a bit more educated! We are away on holidays for a week starting tomorrow so I'll have to come back to the problem when we return.
No doubt there's some simpl(ish) solution, will just have to track it down, or failing that, go for a clean re-install and start from scratch!
All the best,
Tim