The couple Harry (Robert Young) and Tacey (Maureen O'Hara) find themselves searching for a replacement housekeeper when their previous one leaves, owing to a fondness for beer. They place an ad and receive a reply from someone calling himself "Lynn Belvedere," and that name pretty much explains everything! Initially doubtful of this somewhat haughty gentleman, they quickly realize how valuable his help is, even though having him around draws the unwanted attention of local busybodies—chief among them Richard Haydn’s wonderfully entertaining, and frankly quite exasperating, “Appleton.” It becomes clear, however, that "Mr. Belvedere's" privacy hides a reason that will ultimately bring all the neighborhood women together! The film provides some amusement; there’s a pleasant rapport between Young and O’Hara, and their older son, Larry (Larry Olsen), is quite charming as well, but it’s Webb who truly shines. Walter Lang keeps things progressing at a good pace, and the writing often contains clever lines and sharp remarks from the nanny, who proves capable of handling everything from appliance repairs to deliveries. The humor is mild and agreeable, and the acting contributes to an enjoyable 80 minutes filled with observation and consequences for meddling.

Source on TMDB