Yes, well done CAT, it was indeed in Appledore and designed to defend against an invading force crossing the Royal Military Canal. The Pill Box is sited at 51°01'39.5"N 0°47'23.0"E and is visible on GSV.
From here, our walk took us along the Military Canal before striking across fields to Stone in Oxley village and back to Appledore where we enjoyed a well earned tea and cake in the Tea Shop in Appledore village.
Over to you CAT