I can confidently say this is my absolute top choice among Ealing Studios comedies; I suspect many others feel the same way. It's an exceptionally crafted and darkly humorous film, particularly highlighting Dennis Price’s performance as Louis, who truly shines in the central role. There's also a then-young Alec Guinness, playing an astonishing eight different characters throughout the movie! During that period of his career, Mr. Guinness was consistently pushing himself and those he worked with to demonstrate what he could achieve. He had already done so successfully the previous year with his wonderful depiction of Fagin in Oliver Twist, which happened to be only his second film appearance. This remarkable third project effectively put an end to any lingering doubts about his talent, setting him on a path toward a long and impressive career.

Source on TMDB