I have tried using Backup Reports only and then restoring from it but that hasn't worked. I found a Sage article bit found that a bit of a technical fix especially given that I will be asking a client to deal with it. (And to be fair I didn't understand it myself).
Many thanks to all who read this. Very many thanks to all who respond.
PS Anyone else finding the Sage "Priority" Line answering times disappointingly long (50/60 minutes)?