“Their Finest “ is a movie about making a movie, specifically a glossy propaganda film meant to bolster morale in Britain in the darkest days of the Second World War. It is also very much a movie-movie. Good-looking, finely acted, and well-told, director Lone Scherfig (“An Education”) has made a charming, witty and romantic gem. It is “Shakespeare in Love” in World War II.
Adapted by Gaby Chiappe from the novel “Their Finest Hour and a Half” by Lissa Evans, “Their Finest” is centered on Catrin Cole (a luminous Gemma Arterton), a copywriter hired by the government to help write the “slop,” or female dialogue, for a film meant to lift the spirits of a war weary citizenry.