Immediately after John Lennon’s death, Cynthia Lennon reluctantly let her son, Julian, visit Yoko Ono in New York. Julian was still a teenager, and Cynthia didn’t want him to travel alone.

In 1990, Cynthia Lennon contacted Yoko Ono about setting up a benefit concert on what would have been John Lennon’s 50th birthday. She hoped to televise the show and donate the proceeds in her ...