Hiram Draper, a cotton mill owner and a chauvinistic American who dislikes anything British, leaves Texas for London on a business trip with his wife and son. En route, his son, Junior, meets and falls in love with Elinor, an English girl, and determines to marry her even though his parents disapprove. In London, he conspires to have his parents meet Lord and Lady Worthing at a party; and to prove that his son’s judgment is askew, Hiram lives up to the English conception of the uncouth, uncivilized American on a shooting match with Lord Worthing and in his humorous dabbling in international politics. But when Hiram meets Elinor, he instinctively senses that he has been wrong and smooths out matters. More on Wikipedia or Mubi
Watch So This Is London (1930)