I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission not required.
Lock no.3 of the Lagan Navigation, known locally as McLeave's Lock is part of Lagan Valley Regional park AONB. It was disused for a long time but then a few years ago the lock and adjoining lockkeepers cottage were restored as a tourist attraction. Recently there have been plans to restore part of the canal for navigation and in September 2021 a new bridge was opened downstream at Stranmillis and a brand new lock to allow navigation is due to open soon. Notices at the lock showing prohibited activities do not include drones. (Please note that DJI drones will give you Geo Zone warning here but will not prevent flying).
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 21/09/2021. It remains the responsibility of any pilot to check for any changes before flying at the same location.