I have only been questioned once, though to be honest i am lucky to mostly fly in private estates. I was flying over a Scottish castle, which has been closed for months, its miles from anywhere, and no one was about, the carpark was empty. After i guess 15 minutes of flying a game keeper stopped next to us and said we were not allowed to fly there, and that there was a sign (obscured due to undergrowth due to lockdown) telling us it was not allowed. We had the footage we wanted, so thanked him for pointing this out and pointed to the drones, which by now were well away from the castle, and explained we were well away from the area of concern, but were happy to stop and move away. We landed and moved away. It was painess for all parties. I think a few lessons were learned. Firstly, that the rules are stupid, this is a semi derelict castle, closed to the public, outwith bird nesting time, miles from anyplace and the car park was empty, so i can think of no problem with being there. I understand all the reasons why flying there could be an issue, but these were all null and void at this time, but also that the keeper was told no one can fly here so he was doing his job, no bother. Secondly, if i wanted footage of a place like this again, i would take off from some place off the area of concern. That way i would be legal, or as legal as possible. Its academic to me, as its not a thing i am interested in, and only did this as the castle in in lockdown, and next door to where i fly, i am really not interested in these things, it was a one off, job done. I thought it would be ok and missed the sign. We did wonder if it was an issue but honestly 2 of us missed it. Anyway, no harm done, and we got some cool footage. It will never be seen on line!