Holiday Affair (1949): Robert Mitchum Spreads Holiday Cheer
When Connie (Janet Leigh), a comparison shopper (essentially a spy from a rival department store) tries to pull the wool over store clerk Steve Mason’s (Robert Mitchum) eyes, he sees right through her, but he lets her go on her way without informing store security. This leads to Steve finding himself out of a job right before Christmas. It also leads Steve to find himself having lunch with Connie Ennis in the park and helping her with the rest of her day’s work. The pair hit it off, but when Steve returns a load of packages to Connie’s apartment, he meets up with her fiancé Carl (Wendell Corey) and her son Timmy (Gordon Gebert). Unfortunately for Carl, Timmy doesn’t like him nearly as well as Mr. Mason, and that soon drives a wedge between Connie and her soon-to-be husband. Through a series of events that involve a toy train that Steve, though unemployed, gives to Timmy for Christmas, the film unfolds a series of events that thrust Steve and Connie together time and time again until they can no longer deny circumstance.
I couldn't find a trailer, but I did run across 1955 Lux theater TV version of the tale, but it doesn't have as much charm as the Leigh/Mitchum version.