In Disney's Mary Poppins Returns, the lamplighter who helps Mary is named Jack.
Jack is a cheerful London lamplighter played by Lin-Manuel Miranda. He knew Mary Poppins as a child because he was an apprentice to Bert, the chimney sweep from the original 1964 film. Jack becomes an ally to the Banks family when Mary returns to help Michael and Jane.
Jack's occupation links the sequel to a changing London, where gas lamps are being lit each evening. Miranda also performs several songs, including “Underneath the Lovely London Sky” and “A Cover Is Not the Book.” The character is not Bert: Dick Van Dyke's Bert appears in the original film, while Jack is the sequel's new musical companion.