Sean wrote: “Happy Birthday Julian! (Hard to believe that thing on a wall is what we used to call a ‘telephone.’)
John and Yoko’s son was referring to the wired landline phone in the top right of the picture.
Julian was clearly touched by these posts, plus messages from fans, as he posted: “Thank You for your lovely Birthday wishes!”
Last October, John’s sons took part in a special BBC Radio 2 show featuring Sir Elton John and Sir Paul McCartney to celebrate what would have been the late singer’s 80th birthday.