It’s surprising to consider John Wayne alongside Richard Attenborough, but they appear together in this film, and I found myself liking it more than I anticipated. Wayne portrays an unconventional Chicago police officer dispatched to London to apprehend "Larkin" (played by John Vernon). The story unfolds as he and "Sir Charles" are enjoying drinks at a refined club when Larkin is abducted from his sauna; subsequently, this unexpected partnership—aided by the spirited “Jennifer” (Judy Geeson)—must locate him. Wayne seems to be having a good time throughout, and while the storyline is entirely foreseeable, it includes an entertaining car chase and some unexpectedly destructive bathroom fixtures. It's not exactly a masterpiece, but the film maintains a brisk pace for nearly two hours, showcasing two performers clearly enjoying themselves enough to make it worthwhile for the audience. Looking back fifty years later, it’s also fascinating to observe a London docklands setting that no longer exists—and there's a rather clever plot development near the conclusion.

Source on TMDB