If I am reading the situation correctly, the CAA are the only body in the UK that can authorise or prohibit drone flying of any sort. So when a council or any other body or person says that you cannot fly your drone (according to the CAA’s Drone Code), what they mean is that you are not allowed to use their land to TOAL, and they have no authority over where and when you fly the drone. Have I got that right?
If so, then the situation is that you are prohibited from TOAL in Buckinghamshire parks. But you can fly over them within the Drone Code to your heart’s content, and they can’t touch you for it so long as you TOAL from outside the park fence.
I’ve done something similar to this at Cardiff Castle; ‘drone flying’ (by which CADW, the body responsible for the site means TOAL) is prohibited within the Castle but you can TOAL from the park or public highways outside ti and overfly it.
This means that you have to take care, as you will need to maintain VLOS to ensure good RC-drone signal, so you can’t fly low within the castle walls where you can’t see what is going on, but I’ve got some good footage of the castle ineterior from sufficient altitude to see it while standing 50m or so outside the walls. A similar approach should work for parks in Bucks.
The general advice to just go ahead and fly until you are challenged is, I think, good advice. You can show evidence that flying is permitted, and then apologise and move away somewhere else; I very much doubt that the sort of minion who will be approaching you on the ground will follow it up beyond reporting the events to his superior.
You would probably run into problems if you went back to the same site and tried again, especially if the same minion challenges you! So fly from outside the fence…
I am perhaps lucky in that the two encounters I have had with security have both been quite positive. One was outside Cardiff City Hall, where the entrance security guy came over to see what I was doing, He was fascinated, and once he was happy that I was flying safely and considerately left me alone after a not unpleasant conversation. The other occasion was flying Caerphilly Castle; an xmas funfair was set up just over the road and security came over because ‘the boss has asked me to ask you not to overfly the fair in case one of the rides hits your drone’.
Fair enough, some of them went up a fair way and were whirling about at some speed! I explained that I wasn’t allowed to fly over crowds anyway and showed him that I was flying only up to the fence; I could get all the fairground lights dusk shots I wanted from there. He was also interested, and impressed, not having seen live drone images before (look, there we are, wave at Mr.Drone), and came back a little while later with thanks from ‘the boss’ and a lady security, who I think was probably his girlfriend, to show her. I think I know who probably got a drone for xmas…