As detailed in Beatles In They're Own Words
by Barry Miles, Paul McCartney wrote this at his place on Cavendish Avenue in London on the harmonium in the dining room. His Aunty Jin, Uncle Harry, and other relatives were there, and he just sat and wrote it for a few hours with the door opened so they could all listen from another room. Paul said, "I was basically trying to say your mother might know more than you think she does. Give her credit." He also said that the family atmosphere and his Aunty Jin being there influenced it and its music-hall idea.
Julia - OH