Image caption Mr Johnson said the feet at the front of the shot were thought to be Yoko Ono's

A rare shot of John Lennon and Paul McCartney singing together at the time of the Beatles' demise has been found.

The photograph was taken at the 1969 recording of The Ballad of John and Yoko at Abbey Road Studios in London.

The song was released in May of that year and became the band's last number one single.

Merseyside author Dean Johnson, who has revealed the shot in a book, said it showed a "sad epitaph to the greatest musical partnership".

Mr Johnson was sent the photo by a Beatles fan after appealing for unusual and rare images of the band on Facebook.

He said he had seen "nearly everything" to do with the Liverpool group, but had "never seen" the shot of John and Paul.

"The Ballad of John and Yoko was a unique session as only John and Paul took part and, in a way, was a sad epitaph to the greatest musical partnership in pop history."

He added that the feet that can be seen in the foreground of the shot were thought to be those of Lennon's wife, the artist and musician Yoko Ono.

The song, written by Lennon about his marriage to Ono, was recorded in April 1969 while the other two Beatles, Ringo Starr and George Harrison, were away.

Lennon released his first solo single, Give Peace A Chance, in the following July and left the Beatles two months later.

The photo is included in Mr Johnson's book The Beatles and Me, which gathers together unusual pictures of and stories about the band.