Best known as the aunt and guardian of Beatles singer John Lennon, she worked at various points in her life as both a nurse and a secretary. During her soon-to-be-famous nephew's childhood, she discouraged Lennon's musical interests.
After her sister Julia Stanley Lennon became separated from John Lennon's father and began dating another man, Smith became concerned about the welfare of the young John Lennon and eventually persuaded Social Services and Lennon's mother to let her raise him.
She was portrayed by actress Kristin Scott Thomas in the 2010 film Nowhere Boy.
Born Mary Elizabeth Stanley, she grew up in Liverpool, England. She married dairy farmer George Smith in 1939. She and Smith had no children of their own, but raised John Lennon from the time he was a small child.
She disapproved of her nephew's first wife, Cynthia Lennon.