Lennon was extremely fearful of the practice of cremation, and despite this, Yoko chose to burn the Beatle. I’m sure she was aware of his feelings, because he had once wrote against the practice in a song.
According to the documentary, “The Real John Lennon,” none of his family in England were consulted about what to do with his remains. In fact, in his Will, only his son Sean is mentioned, nothing is said about Julian.
Former assistant, Frederic Seaman, against Yoko’s wishes, wrote an excellent book about John Lennon entitled, “The Last Days Of John Lennon.” In it he said, that MacDougal who was present at the cremation, said that John’s face was serene and calm up until it was time to go into the oven. Then suddenly it turned into a “pained, macabre grin,” "they" say due to rigor mortis.
There are conflicting stories as to what happened to his ashes. Some say Yoko scattered him on Strawberry Fields, others say she still has them.