She grew up in the middle-class section of Hoylake, on the Wirral Peninsula in North West England.
At the age of 12, she was accepted into the Junior Art School, and was later enrolled in the Liverpool College of Art.
She married Italian hotelier Roberto Bassanini in 1970, divorcing him in 1973.
In 1976, she married John Twist, an engineer from Lancashire, but divorced him in 1983.
John Lennon also attended the college; a meeting with Powell in a calligraphy class led to their relationship.
After Powell became pregnant, she and John were married on 23 August 1962 at the Mount Pleasant register office in Liverpool and from 1964 to 1968, they lived at Kenwood in the Surrey town of Weybridge, where she kept house and participated with her husband in a London-based social life.In 1968, John left her for Japanese avant-garde conceptual artist Yoko Ono and as a result, the couple's divorce was legally granted on 8 November 1968 on the grounds of John's adultery with Ono.