India, Sept. 16 -- Earl Charles Spencer has claimed that King Charles told him in a heated phone conversation just days after Princess Diana's death that the public's overwhelming grief for the late princess would fade quickly, according to an explosive forthcoming memoir that threatens to reopen old wounds within the royal family, BBC is reporting.

The allegation appears in Spencer's book, titled Swan Song: Diana, My Sister, scheduled for release on 22 September, and marks the most significant public accusation the Earl has made against the King since delivering his internationally renowned eulogy at Westminster Abbey in 1997.

In the memoir, Spencer writes that King Charles "hissed" the remark "Rest assured, we'll forget her soon enoug...