The child agent (is played by a very young Barry Gordon, who may be best known on TV for his role as "Gary Rabinowitz", the boyfriend of Archie Bunker's niece Stephanie, in the "All in the Family" spin-off, "Archie Bunker's Place" (which aired 20 years after this Jack Benny episode).
In the movies, Barry played the young ward of Jason Robards' eccentric character in the bittersweet 1965 comedy "A Thousand Clowns".