It looks like the CAA pages and drone code have been improved to make it clearer that we dont necessarily need permission from the landowner of the land being flown over. The “Where you can fly” page says to get permission from the landowner where you “take off and land”. It then leads to another page that quotes “where you can fly from”, the important word there being “from”. Not sure it was that clear last time I checked?
There’s also been a statement from the Counter Drone Team at the National Police Chief’s Council, in this Geeksvana video, where police stated “the legal stance is they don’t own the airspace the airspace is open let’s keep that nice and simple”.
FPV UK Article 16 authorisation also alludes to the same in the notes “Although there is no regulatory requirement to obtain permission to operate within controlled airspace, remote pilots are reminded…” … and lists some negligence rules.
I would say things are pretty clear now. Though I’ve also found some court cases that seem to show that flying low or close to buildings could be considered that the drone is on the land, thus tresspass and local byelaws would apply. I think that if you’re above the airspace used by the landowner, i.e above any trees or buildings, and flying responsibly then you’re legally fine in this regard.
2024-2025 also saw a lot of social media “audits”, where people tested the right in practice. One channel has a playlist of over 55 video encounters with the National Trust alone. In some of them the police are called as the auditor baited the staff. The police turn up, initially side with the Trust of course, and then as they make their enquiries the case unravels and the Trust staff are told that no offence has taken place. In the more recent audit videos from last few months it’s clear that the Trust have now advised staff not to approach anyone standing outside of their property.
Stating the obvious: I’m some shmo on the internet, not a lawyer, just a keen reader, make your own enquiries and judgement. I’m just sharing my thoughts.