"Goodbye" is a song written by Paul McCartney (but credited to Lennon–McCartney) and performed by Mary Hopkin. It was released on 28 March 1969, and it reached No. 2 in the UK singles chart, prevented from reaching the top position by the Beatles' single "Get Back". In the US, released 7 April 1969, the song reached No. 13 on the singles chart. In the Netherlands the single peaked at No. 1.

The song was conceived as a follow-up to the success of Hopkin's first single, produced by McCartney, titled "Those Were the Days", which was highlighted on her debut album Postcard, one of the first records issued by the newly founded Apple Records. In later years, McCartney had little recollection of creating the song, which was written in a great hurry to capitalise on Hopkin's popularity, but he did recall being told by a boat skipper from the Orkney Islands that it was the man's favourite song, which seemed appropriate to McCartney since, "if you think of it from a sailor's point of view, it's very much a leaving-the-port song."Allmusic critic Richie Unterberger described it as a "pleasant and catchy romp, rather like a Continental European folk love ballad in tone, with a dash of music hall."

To assist Hopkin in learning the song, McCartney recorded a solo demo at his home, 7 Cavendish Road, London, in February 1969. The song was arranged by Richard Hewson, who had also orchestrated "Those Were the Days," and produced, along with its flip side, "Sparrow", by Paul McCartney on 1 March 1969 at Morgan Studios in Willesden. To better match Hopkin's voice, the key was raised from C major to E major. The recording was Apple's first official double-A-side, and the first Apple record to feature a full-fledged picture sleeve.

For the recording, Hopkin sang and performed acoustic guitar, while McCartney played bass guitar, an acoustic guitar introduction and solo, along with lap-slapping percussion and drums. Backing vocals, horns and strings, in Hewson's arrangement, were overdubbed. The session was filmed by Apple's Tony Bramwell for a promotional clip. In the footage, Hopkin can be seen miming to the song inside the studio, combined with shots of her and McCartney in the control room listening to a playback.

...
Wikipedia