A while ago now I appealed to the ICO and made the case that the Duchy of Lancaster is a public authority for the purposes of the Environmental Information Regulations.
The ICO essentially said that the Duchy was a private estate and not a public authority but I asked them to look again and to their credit they did and the case has been re-opened:
“I am grateful for the arguments submitted and the issue has been the cause of much debate. In short, I have decided to re-open the case and complete a more thorough examination of the facts presented. This does not necessarily represent a change of outcome, but simply an opportunity to re-evaluate the issue as a whole, as I felt that a simple case review on my part would not have done the matter justice.”
I have also found out that the Duchy of Lancaster itself is not registered but the Chancellor of the Duchy of Lancaster is listed (see http://www.ico.gov.uk/ESDWebPages/DoSearch.asp?reg=4146633). It would appear that a Government Minister is the data controller for all of the Duchy of Lancaster’s activities. It would be impossible to act as data controller for all the personal data of tenants without also controlling at least some ‘environmental information’ about land and buildings. This adds weight to my case that Duchy data is data held by a public authority.