As noted in the opening caption, the action of the film takes place during the year preceding the Second World War (beginning with the German invasion of remaining Czechoslovakian territory in March 15th 1939) and closes on the night of Sunday September 3rd 1939 (the day the United Kingdom declared war on Germany).
The very first scene is a fairly accurate depiction of the Berghof, Adolf Hitler's mountainside residence near Berchtesgaden and Obersalzberg in Bavaria. The home was famous for its huge picture window which overlooked mountain scenery and was often used to impress visiting foreign VIP visitors.
The last of seven films Margaret Lockwood made with director Carol Reed. The others are _Midshipman Easy (1935)_; _Who's Your Lady Friend? (1937)_; _Three on a Weekend (1938)_; _A Girl Must Live (1939)_; _The Stars Look Down (1940)_; and _Girl in the News (1940)_.