The key is to follow the key! The Long Arm is directed by Charles Frend and written by Janet Green and Robert Barr. It stars Jack Hawkins, John Stratton, Dorothy Alison and Michael Brooke. Music is by Gerard Schurmann and cinematography by Gordon Dines. Detective-Superintendent Tom Halliday (Hawkins) heads up an investigation into a number of safe cracking robberies. Which in turn turns into a murder investigation. Out of Ealing Studios, this is a little cracker of a police procedural detective mystery. The flow of the investigation is natural, not given over to wild implausibilities, and always the air of mystery is potent. On the outskirts of the investigation there's a running thread about how policemen's wives/girlfriends suffer in their own ways, their men are married to the force, and this is delicately handled by the makers. While the moments of wry levity are not misplaced. Production is spiffing, with a number of London locations vibrantly used and given a film noir sheen by Dines (The Blue Lamp), while Frend (Scott of the Antarctic) keeps it tight and interesting whilst getting grand perfs from the cast - notably a wonderfully regal Hawkins. So if you are looking for an old time British policer that doesn't insult your intelligence, then you need look no further. 8/10