In relation to Data Protection etc, my understanding of this for us flying Multi rotors is that it doesn't apply.
The data protection act was designed to protect individuals from companies ie banks , local authorities, law enforcement, and others from collecting personal data on an individual or company etc,who can be identified from the data and this data used to profile the individuals , companies activities. The retention of that data by such bodies has to be justified for retention, ie that individuals human rights under that act, it has to have a purpose, ie for Prevention of crime, or to assist the bodies in a lawful purpose, ie Heath records, or for banks to see if they will give you a loan etc, the list is massive..
However it all pertains to one thing... Can the individual be identified and was the purpose of the say" photography" directed to capture the individual which I would suggest in the case of the majority of film photos it isn't
If it did capture someone in a park or on a walk etc, does or can the data be used for a purpose, generally not.
It's the same as you taking a photo in your town or village , those images are not subject to the data protection act.
Anyway I could go on , but that's my understanding, it only becomes "surveillance " if it's specifically directed to an individual or company for a purpose that relates to that company or individual .