Filed at 6:45 p.m. ET LONDON (Reuters) - Paul McCartney is to release a Beatles track unheard for 35 years as the soundtrack to a film montage of his late wife Linda's photographs, The Sunday Times said. The 14-minute ``Carnival of Light,'' first recorded by the Beatles when they were making their Sgt. Pepper Album, had last been played at a London avant-garde festival in 1967. Beatles producer George Martin was quoted by the paper as saying: ``It was one of those weird things. It was a kind of uncomposed, free-for-all melange of sound that went on. ``It was not...