Thanks guys,

Phil's method works. It seems much more sensible that putting a lock on the table. Thanks for the lock info as well.

So to cut a long story short, what should I do to reliably catch teh error (and rollback the transaction)?

Perfect!

Thanks again for your help (for the second time today!!)

Thanks for the pointers guys, I'll give it a go.

Fair point! Thanks for the reply.

Thanks, I'll give it a go.