Paul McCartney paid a heartfelt tribute to John Lennon on the anniversary of his death, revealing it was a "sad, sad day".
The singer, 78, shared a throwback picture of them together, taken by Paul's former wife Linda McCartney, and wrote alongside it: "A sad sad day but remembering my friend John with the great joy he brought to the world.
"I will always be proud and happy to have known and worked with this incredible Scouser! X love Paul #JohnLennon."
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The black and white never-before-seen snap shows Paul and Lennon together in a recording studio, with John holding a chocolate digestive biscuit. Both of them can be seen attentively listening to someone off-camera.
Fans of the Beatles were quick to react to the sweet message, with one commenting: "That's nice of you to say Paul, John will always be the best ambassador for scousers."
A second added: "40 years today the world lost one of the greats in music, we will always remember. Peace and love!" whilst a third remarked: "Love everything you two wrote. 40 years later, I still can’t believe he’s done. What a loss."
Yoko Ono also paid tribute to her husband, writing: "The death of a loved one is a hollowing experience. After 40 years, Sean, Julian and I still miss him. 'Imagine all the people living life in peace.' Yoko Ono Lennon #enoughisenough #peace #guncontrolnow #gunviolence #nra #guns #gunsafety #firearms #endgunviolence."
The 87-year-old accompanied the post with a poster that highlighted the seriousness of gun violence in the U.S.
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Ringo Starr also took to Twitter and, alongside a picture of him and John together, he urged radio stations across the globe to play Strawberry Fields Forever in his former bandmate's honour.
"Tuesday, 8 December 1980 we all had to say goodbye to John peace and love John. I'm asking every music radio station in the world sometime today play Strawberry Fields Forever. Peace and love," he wrote.