Hi DSPatrick,
I checked the log files in the 'Panther' folder, and found several errors (0xC1800104 and others).
Ran the following commands:
Dism /online /cleanup-image /scanhealth
Dism /online /cleanup-image /checkhealth
Dism /online /cleanup-image /restorehealth
And the installation is now progressing!
Many thanks for your help,
ALlen