Hi Edgar,
Thanks for your reply. To answer your questions:
1. I am using duplicity 0.7.10
2. I did do the dance as described in "a note on PyDrive". I am using a regular account to store the backup so I created the client ID and client secret for the Drive API. The bit I am missing is the last sentence of the note. I run my backup, it asks me to visit the URL to authorise access to my drive but it never cache's my verification so I must re-authenticate every time I run the backup.
3. I have --allow-source-mismatch on after I tided up our DNS server. The reverse lookup had a different hostname than the fileserver so Duplicity wouldn't increment the existing backup. Is using that flag bad practice?
Thanks again
Owen