Short answers, pulled from the story.
Paul McCartney wrote the song based on a 1963 newspaper article about seventeen-year-old Melanie Coe who ran away from her home on Stamford Hill. The Daily Mail reported that she left because her parents were too overprotective and stifling.
George Martin conducted the string section for the song on the 17th of March 1967 after Mike Leander took over the arrangement task. This marked the first time a Beatles song lacked an arrangement by their longtime producer George Martin.
Engineers sped up the final mono mix to make Paul McCartney sound younger than he actually was while the stereo version remained at the original tempo. This created a discrepancy where the stereo version sounded a semitone lower than the mono release until Giles Martin remixed the stereo version again in 2017.
Lennon and McCartney won the 1967 Ivor Novello award for Best Song Musically and Lyrically as credited composers. Composer Ned Rorem once described the track as equal to any composition Schubert ever wrote.
Billy Bragg recorded a version of the song with Cara Tivey that reached number one on the UK Singles Chart in 1988. Both tracks came from the charity fundraising album Sgt. Pepper Knew My Father.