Rising Damp S3E6 (The Cocktail Hour)

Alan is dating the upper class Caroline Armitage and, when Ruth says that Caroline's mother is a wealthy property owner, Rigsby is keen that Alan gets engaged to her so that he can benefit by it. He gives the lad lessons in etiquette in anticipation of a tea party for Mrs Armitage but is angry to find he has not been invited. When he crashes the party he discovers that Mrs. Armitage is the former Mabel Bagworthy, a common rag-and-bone man's daughter that he was at school with, who rode to school on her father's cart, and he takes great delight in telling everyone. Needless to say,the engagement is off.