The Ballad of Beatles and Yoko
John and Paul spent April 14, 1969 recording The Ballad of John and Yoko. During one of the days shortly thereafter, the Beatles and Yoko gathered for a quick photo session to promote the single's release. The location for the session, with Linda McCartney as photographer, was the garden at Paul's Cavendish Road home. The Ballad of John and Yoko was issued as a single, backed with George's Old Brown Shoe, on May 30th 1969 in the UK and June 4th 1969 in the USA. The American release came in a picture sleeve featuring two pictures from this photo session.
Paul seems to have favored yellow socks during this period. He was also wearing them during the Voyage of the Fritz photo session on April 9, 1969.