The Mellotron is an electro-mechanical, polyphonic tape replay keyboard originally developed and built in Birmingham, England in the early 1960s. It superseded the Chamberlin, which was the world's first sample-playback keyboard intended for music. The concept of the Chamberlin was itself modeled after the Laff Box invented by engineer Charlie Douglass in order to insert prerecorded laughs into TV and radio programs more easily in the then-developing field of post-production.

The heart of the instrument is a bank of parallel linear magnetic audio tape strips. Playback heads underneath each key enable the playing of pre-recorded sounds. Each of the tape strips has a playing time of approximately eight seconds, after which the tape comes to a dead stop and rewinds to the start position. A major advantage of using tape strips, as opposed to tape loops or cassettes (cf. the Birotron) is that the Mellotron can reproduce the "attack" transient of the instruments recorded on the tape. A drawback is the short "decay" time of the note.

Sir James Paul McCartney, MBE, Hon RAM, FRCM (born 18 June 1942) is an English musician, singer-songwriter and composer. Formerly of the Beatles (1960–1970) and Wings (1971–1981), he has been described by Guinness World Records as "The Most Successful Composer and Recording Artist of All Time", with 60 gold discs and sales of over 100 million albums and 100 million singles. With John Lennon, George Harrison, and Ringo Starr, he gained worldwide fame as a member of the Beatles, and with Lennon formed one of the most celebrated songwriting partnerships of the 20th century. After leaving the Beatles, he began a solo career and later formed the band Wings with his first wife, Linda Eastman, and singer-songwriter Denny Laine.

According to the BBC, his Beatles song "Yesterday" has been covered by over 2,200 artists—more than any other song. Wings' 1977 release, "Mull of Kintyre", became one of the best-selling singles ever in the UK, and he is "the most successful songwriter" in UK chart history, according to Guinness. As a songwriter or co-writer, he is included on thirty-one number one titles on the Billboard Hot 100, and as of 2012 he has sold over 15.5 million RIAA certified units in the United States.