There’s no question that the overall success of the Beatles was made possible through the contributions of Sir George Martin. He was responsible for many of the musical and technical innovations that appeared on their 12 studio albums recorded between 1962 and 1970. He is often referred to as “The Fifth Beatle” because of his importance to the group. Recently, David Bennett reviewed George Martin’s contributions in detail, specifically the parts where his performances appear on the recordings.
In various interviews, Martin stated that he initially wasn’t impressed with very early Beatles recordings, but appreciated the band’s dry wit (especially George Harrison’s), and – based on that – agreed to sign them. He worked closely on their first releases, specifically “Love Me Do”, “P.S. I Love You”, and “Please Please Me”, often providing polish or music arrangement sensibility. The latter song went on to reach #1.
Though his contributions initially involved listening and brainstorming suggestions for songs by Lennon and McCartney, he began contributing actual musical parts to some performances. In many cases, he wrote, arranged, and conducted background movements. In others, he’d perform certain parts either because Paul or John couldn’t play them well enough, or the band needed additional “hands.”
Source: Will Wills/culturesonar.com