Cogan lived with her widowed mother in Kensington High Street (44 Stafford Court), a lavishly decorated ground-floor flat, which became a legendary party-venue. Regular visitors included Princess Margaret, Noël Coward, Cary Grant, Audrey Hepburn, Michael Caine, Frankie Vaughan, Bruce Forsyth, Roger Moore and a host of other celebrities.
She was close friends with the Beatles, even though the teenage Lennon used to mimic her savagely during his time at the Liverpool College of Art. However, they would largely eclipse her fame. Paul McCartney first played the melody of "Yesterday" on Cogan's piano, and also played tambourine on her recording of "I Knew Right Away".
In a Daily Mail interview, Cogan's sister Sandra, who was briefly linked to McCartney, claimed that Cogan had a serious romance with Lennon that had to be kept secret because of her family's strict Jewish faith. Her last romance was with Brian Morris, who shared her faith. They were engaged to be married.
After Cynthia Lennon died, Lennon's biographer published her previously unpublished quotes regarding Cogan, whom Lennon met in 1964 on TV pop show Ready Steady Go. "John thought I didn’t know anything about him and Alma, and I never let on," Cynthia Lennon said. "Now that I think about it, with all the emotion gone out of it, I can see the attraction. Alma was about eight years older than John and very much the Auntie figure. Don’t forget that Yoko was also older than John by about seven years. Like Yoko in so many ways, Alma was a very compelling woman. You couldn’t really say that either of them was beautiful, could you, not in the conventional sense. When Alma died from ovarian cancer, aged only 34, John was inconsolable."