It was directed by Brian Desmond Hurst and starred Mary Clare and Martita Hunt as two sisters, Caroline and Edith Grant, who have to deal with two invading Germans who arrive at their cottage.
The film opens with sisters Caroline (Mary Clare) and Edith Grant (Martita Hunt) preparing to shelter in their cellar following an air raid warning.
When Edith informs the ARP warden of the situation, he calls the Local Defence Volunteers (Home Guard), interrupting a lecture on German parachutists.
The final scene depicts the Grants thanking a member of the LDV over a cup of tea in their cottage, and he commends their actions with the words: 'You kept your heads.
Reviewers highlighted the fact that the film was flawed in terms of the advice it offered because 'most of us have no revolvers' and in the event of invasion, they could not rely on dead Germans to supply them.
Released in hardback on 15 September 2016 with almost 400 pages and over 350 images "this book also shows why Hurst was an enigma, but a master of the genre, and at his very best when focusing on the vast canvas of film" (from dust jacket).