Hi Aderson,
Thank you for your reply and suggestion.
I did try a backup and restore but ran into permissioning issues. I eventually realised that the SQL service which is accessing the file needs to have permission to the database files which are not in the default directory for SQL Server Management Studio (SSMS). Looking at the properties for the service I found that this was running as 'NT Service\MSSQL$SQLEXPRESS', I then added that to the 'groups and usernames' section of the folder containing the database files.
I was then able to perform the backup and restore successfully.
I then needed to rename the database as described here:
https://www.mssqltips.com/sqlservertip/4419/renaming-physical-database-file-names-for-a-sql-server-database/
One thing though, I couldn't take the database offline, that option caused the SSMS interface to hang.
So I stopped the SQL Service instead.
It was a bit long winded but I now have a copy of the database with new physical and logical file names correctly changed.
Thank you once again for your suggestion.
Best Regards,
Steve