Britain's Ministry of Information produced or sponsored a range of short films during World War II. Some were stirring and inspiring, like Words for Battle , narrated by Laurence Olivier, or Britain at Bay , written and narrated by J. B. Priestley. Others were informative, passing on important messages. These included a series on the dangers of "careless talk" , as well as individual films about the importance of observing the blackout ( Mr. Proudfoot Shows a Light ), how to deal with incendiary bombs ( Go to Blazes , with the comedian Will Hay), what to put out for salvage ( Salvage with a Smile ) and how to grow your own veg (Dig for Victory ). But 1940's Miss Grant Goes to the Door offers a more sobering lesson - how to act during a German invasion.