(Web Desk) - After a week of build-up, The Beatles have released what's been billed as their "final song".
Called Now And Then, it's been 45 years in the making - with the first bars written by John Lennon in 1978 and the song finally completed last year.
All four Beatles feature on the track, which will be the last credited to Lennon, McCartney, Harrison and Starr.
And in a full-circle moment, it's being issued as a double A-side single with their 1962 debut Love Me Do.
Simultaneously, the song arrived on streaming services like Spotify, Apple Music and Amazon Prime Music.
CD, vinyl and cassette copies will be available the following day. And from 10 November, the song will be included on the newly remastered and expanded versions of The Beatles' Red and Blue greatest hits albums.
The original demo has circulated as a bootleg for years. An apologetic love song, it's fairly typical of John Lennon's solo output of the 1970s - in a similar vein to Jealous Guy.
It was finished in the studio last year by Sir Paul McCartney and Sir Ringo Starr. George Harrison will appear via rhythm guitar parts he recorded in 1995, and producer Giles Martin has added a new string arrangement.
"Hearing John and Paul sing the first chorus together, as they lock into the line 'Now and then I miss you' - it's intensely powerful, to say the least," said Rob Sheffield of Rolling Stone magazine.
"I cried like a baby when I heard it," added BBC 6 Music's Lauren Laverne. "Just gorgeous."