The Home Guard were volunteers in the Second World War. Their job was to protect the country as best they could should invasion occur.
The Home Guard was a kind of reserve army of last resort. They were given few weapons, for these were needed by the troops fighting abroad. So they had to make do with whatever weapons they could find.
It was also a way of making people who were not in the army feel that they had a useful part to play in the war.
Members of the Home Guard who lived along the south and east coasts helped to keep lookout for invasion.
Fortunately they were never needed.