NT are notorious b***ards when it comes to image copyright. I don't know if this has been mentioned in other posts, but they recently ran a photography competition where submitting an image indicated your consent for NT to own the copyright on it!
If you take an image on NT land, they own the copyright, if you take an image outside of NT land, but looking in on it, they still own the copyright.
It would be interesting to see how they would enforce such conditions.
PS: A month of eh! Easy life!