Apologies if this has been repeated elsewhere. The CAA have clarified Local Authorities don’t regulate airspace (though they can of course ban take off and landing on their land). The clarification is contained in the CAA’s CAP 722C
The bit of the CAA’s 722C guidance document that is most relevant, and very useful to be armed with is:
4.3.2 Information for Local Authorities
Whilst byelaws may exist which protect council land, and those using it, these are not UAS Geographical Zones and the management of this airspace is only possible following establishment of an appropriate airspace structure, in accordance with the documents referenced throughout CAP 722C; the airspace remains a State asset, and is managed by the sponsor. As such, the details of these Byelaws will not be promulgated as UAS Geographical Zones within the AIP and will therefore not be displayed on online charts or apps. If Councils deem a UAS Geographical Zone is required in addition to any Byelaws, then they should follow the guidance within this document and the relevant referenced documents.
Only through a legal process to create a byelaw. And those are ripe for challenge.
Hall v. Beckenham stands as case law for the default position of a council without a byelaw on the use of UAS from their land. They are trustees of the land on behalf of the public, not regular owners of land like a private landowner would be. Any council policy on UAS not backed by a byelaw means basically nothing.
The pertinent bit of the judge’s ruling (and this was a case about model aircraft so… you know, clearly applicable to drones or if you’re using an Article 16 operational authorisation) was:
So long as a member of the public behaves himself in the ordinary way, committing no criminal offence and observing the by-laws, the corporation cannot stop his doing what he likes in this recreation ground . . I think that the corporation are the trustees and guardians of the park, and that they are bound to admit to it any citizen who wishes to enter it within the times when it is open. I do not think that they can interfere with any person in the park unless he breaks the general law or one of their by-laws.
If the council claims to have a policy prohibiting UAS but doesn’t have a byelaw covering it, it would be unlawful for them to try to enforce that policy.