The 23rd song credited Lennon/McCartney but recorded by artists other than the Beatles was Paul McCartney's "Goodbye". Paul recorded a demo featuring his singing and guitar playing in February 1969.
The demo was then given to Mary Hopkin to record in the studio, which was done on March 1 and 2 of the same year. Hopkin sings and plays acoustic guitar, while McCartney adds bass, "body percussion" (thigh slaps), and overdubs the guitar introduction and solo. Backing vocals and additional instruments were added, too. Macca also produced the recording, which was commercially released on 28 March 1969.
Hopkin eventually regretted the recording, admitting to Goldmine in 2007, "Although I’m flattered that Paul wrote 'Goodbye' especially for me, it was, I believe, a step in the wrong direction for me. I’m so grateful that he chose 'Those Were The Days' as my first single. I think 'Those Were The Days', being originally a Ukrainian folk song, has a timeless quality, but 'Goodbye' is set firmly in the sixties pop era."
This blog is a workshop for developing my analyses of The Beatles' music.