A fondly remembered studio-based drama, and an example of the sort of superb production that was regularly transmitted on television. 

An Englishman's Castle is a television serial first broadcast in 1978, written by Philip Mackie. The story was set in an alternate history 1970s, in which Nazi Germany won World War II and occupies England. Peter Ingram (Kenneth More) is a writer for a soap opera (also called An Englishman's Castle), which is set in London during The Blitz and subsequent Nazi occupation. 

He is oblivious to Nazi rule, which is hidden behind a facade of seemingly normal English daily life. As is mentioned in historical references, the occupation was followed by several years of guerrilla warfare, which culminated in an amnesty that enabled the resisters to resume normal daily life in return for accepting the reality of German occupation - which they generally did, feeling that further resistance was futile.