If you go on to the National Archives, documents on line, search facility and look for RNVR personnel with AA prefixes, a suprising number come up, 3,031 mainly London Division RNVR so I imagine that there must have been a large number of small AA batteries scattered about.
At the star of the War, the Navy was given the task of aerial defence around London so I'm not at all surprised that there are many London men in your list. I believe that the Army took over this operation later on but I'm not sure when or whether the Navy men continued at the same sites. I don't believe that the Army took over the defence of Naval establishments at any point in the War so there must have been some kind of RN AA organisation throughout the conflict. I have had no reason to research the Navy so I've no idea of how its organisation differed from that of the Army in the way Diaries or their equivalent were kept, for example.
I'll see you at the Cenotaph tomorrow.