loads of previous threads on this, however.
I found the answer is in this document:
Cisco Unified IP Phone 7961G/7961G-GE and 7941G/7941G-GE Administration Guide for Cisco Unified CallManager 6.0 (SCCP and SIP)
but essentially:
Do as explained above to ensure all is correct for the files, then;;
Logon to CCMAdmin
Select OS Administration
Select Software Upgrades
Select Upload TFTP Server File
Enter the Sub Directory as /Desktops/320x196x4 - EXACTLY AS SHOWN
Browse for the List.xml & image files
Click Upload
Restart the TFTP Service;
Select Cisco Unified CallManager Serviceability
Select Tools
Select Control Center - Feature Services
Place radio buttin against Cisco tftp
Click Restart
