Wikipedia
Walmington-on-Sea is a fictional seaside resort that is the setting of Dad's Army, including the BBC Television sitcom, the BBC Radio 4 series and two feature films ( 1971 and 2016).
Walmington is on the south coast of England which, following the evacuation of the British Expeditionary Force from Dunkirk during the Second World War, found itself on the front line against Hitler. It is in Sussex and the nearest large town is Eastbourne, where Captain Mainwaring was educated at the local grammar school.
The series followed the adventures and misadventures of members of a fictional platoon of the Home Guard, a volunteer army formed from those ineligible for conscription by age, minor physical inability or occupation, to defend the United Kingdom from German invasion following the fall of France.