Stuart Sutcliffe and Astrid Kirchherr. Crucial Mod forebears, though German. Or maybe that's where Mod came from. Certainly, electronic music comes from there. And Romanticism kinda started there. And David Bowie.
There were many self-proclaimed '5th Beatles' over the years, but Stuart Stutcliffe, a buddy of John's from art school was the original. Although he had little musical talent, basically "faking" playing the bass with his back to the audience, John insisted that he play with the band. Stuart fell in love with German photographer Astrid Kircherr and left the band. he died of a brain tumor in 1962
Stuart Sutcliffe collapsed in the middle of an art class in Hamburg. Nielsa Kirchherr had German doctors perform various tests, but they were unable to determine exactly what was causing the intense headaches from which he had been suffering. While living at the Kirchherrs' house in Hamburg, his condition grew steadily worse. After collapsing again, Sutcliffe was taken to a hospital by Kirchherr (who rode with him in the ambulance), but he died before reaching the hospital.