In The Crown's season 6 finale, one climactic scene features a song entitled "Sleep, Dearie, Sleep," and there's a deeper meaning to the song. Queen Elizabeth, now 80 years old, spends a moment alone in Westminster Abbey, the church in which almost all British monarchs have been laid to rest. As the song plays, she envisions her own coffin, and younger versions of herself (portrayed by Olivia Coleman and Claire Foy, who played the Queen in earlier seasons of the show) appear behind her, momentarily bringing back every actor who played Queen Elizabeth on The Crown. Queen Elizabeth — and, by extension, the audience — reflects on her reign as the swelling bagpipe melody rings through the Abbey.

https://screenrant.com/sleep-dearie-sleep-song-queen-elizabeth-funeral-explained/