Airspace can be restricted surely by both the CAA and by byelaws.
Gunnersbury park and Hanwell zoo are restricted by byelaw https://www.ealing.gov.uk/info/201132/parks_and_open_spaces/643/park_rules_and_bylaws/5?fbclid=IwAR2vIKj64aEYcW6eWlZ8W2mhY0WLMiTZAsoFVzHt-76nY6yoJpyagoIWUYA
All parks in the borough of Ealing require prior permission for each flight