I have Firefox set up to not accept any cookies except from sites on a white list. I checked to see if there were any cookies from cups and there were none. I also found that cups was on the white list so I removed it. But unfortunately there was still no change in cups behaviour.
What I did do, is set up the printer using the Chromium browser and that name now shows on the list generated by cups/admin > manage printers when using Firefox, so that is some progress, but I still can't change anything using Firefox.