Gullible master locksmith (Drake) is continually duped into using his lock-picking prowess to commit unsuspecting crimes for the dapper con artist Dennis Price and his shady associates. Judge Geoffrey Keen initially sentences him to one year's probation, but after a number of other ruses in which he's left holding the baby, so to speak, he's incarcerated and quickly earns the respect of fellow inmates for his sleight of hand (albeit inadvertent). But a stint in the big house isn't going to cure his credulity and he's duly enlisted in another scam on his release.
Drake looks like Gordon Jackson in Richard Attenborough's stout frame, and he has great comic timing, playing a character so innocent and optimistic, it's impossible not to form sympathy for his constant exploitation. Percy Herbert co-stars as the gaol-house heavy with whom Drake forms an enduring friendship, and the lovely Nyree Dawn Porter is the refined beauty assigned to seduce Drake into a daring safe-cracking job, organised by heavyweight mobster Eddie Byrne. The impeccable cast also features George Sanders, Dennis Price, Finlay Currie and Neil McCarthy (as Drake's slightly unusual cell-mates), Norman Bird and Ronnie Barker in an audition for "Porridge".
Quite typical of the British comedies of the era (in fact the giant marrow scene could have even been borrowed from "Two-Way Stretch"), with more than a few chuckles (the gaol break to collect bird seed or the balloon scene in which Drake is plied with champagne spring to mind) and if there's a criticism, it's the epic near two-hour duration which could have been far more economical. And sorry to disappoint, though Robert Shaw is credited in this movie on IMDb, and no disrespect intended, it's actually Richard Shaw who plays the minor role of "Moke" in the movie.