I am lucky enough to be able to holiday in Brownsea Castle and whilst there recently I decided to try and find the varied remains and sites of the second world war sites that were placed there, several of which are off limits to the general public as they are in the castle grounds.
I have based my search on the information on edob.mattaldred.com/ and went looking looking for the following. I only found two six pounder sites, not three and I found that some of the What Three Words references were a little off (although not by much)
Naval Bombing Decoy e18954 An N Series, or Starfish type naval decoy to help protect Poole Harbour
///birds.across.flies
Machine Gun Post e58267 Based in Horse Field to defend against paratroopers. Not much info available. Open field between two large trees with picnic benches.
///palace.recall.tens
Defended Locality (Farm Buildings) e58264 Near the visitor centre and open building with farm machinery in.
///firmly.taped.move
Defended Locality (Church) e58265 No real information online
///nail.oasis.pepper
Coastal AA Gun Battery (Removed) e27683 Site of 40 mm Bofors(?) guns
///engine.select.straw
Extended Defence Officers Post S0013560 Underground control centre for exploding sea mines in the Channel in the event of invasion. There are two ventilation shafts visible. over the edge of the cliff there are reinforced concrete pieces some 6ft x 2ft. These may be observation windows overlooking the harbour entrance.
///system.miles.descended
Coast Artillery Searchlight S0007722 (Extant) The building is of brick with a concrete roof supported by iron girders. The seaward SE side is open except for a low brick wall. The SW and NW sides are solid brick. Entrance via doorway in NE side.
///actor.pest.covers
Coastal Artillery Battery (extant) S0015050 Six inch gun emplacement. One or two ancillary buildings in reasonable condition. (information from 1982 aerial photographs).
///whites.chefs.scarcely
Gun Emplacement S0007712 Six inch gun emplacement
///orange.funny.calm
Gun Emplacement S0007713 Six inch gun emplacement
///apply.left.hats
Civil Air Raid Shelter (Removed) e53836
///daisy.ally.limit
Coastal AA Gun Battery (Removed) S0007721
///bill.faces.think
Defended building (Removed) e58266
///trade.hills.rather
Plenty more defensive bits and bobs on the mainland but there are also some bits on the islands around Brownsea. Furzey Island had and air raid shelter, Green Island behind it, and Round Island to the West had a solitary AA gun position.