Paul,
Thanks very much for all your help.
I'm not sure if my clients will accept the workaround as they say that it is a legacy schema that cannot be altered.
My firm is not a SAP partner so I can't log a Tech Support Incident (it appears; please correct me if I am wrong) so I will ask the customer to do so. If they do and supply the incident number I will update this thread.
Thanks again,
Dave.