Originally titled "Seventeen", the song was conceived by McCartney when driving home from a Beatles' concert in Southport, Lancashire as a modern take on the traditional song "As I Roved Out", a version of "Seventeen Come Sunday" that he had heard in Liverpool in 1960. According to Beatles biographer Mark Lewisohn, McCartney first worked out the chords and arrangement on an acoustic guitar at the family home of his Liverpool friend and fellow musician Rory Storm on the evening of 22 October 1962. Two days later, McCartney was writing lines for the song during a visit to London with his then-girlfriend Celia Mortimer, who was seventeen at the time herself. The song was completed about a month later at McCartney's Forthlin Road home in collaboration with Lennon and performed as part of their set in December 1962 in the Star Club in Hamburg.