Charles Spencer's Diana book tops Amazon bestseller after release

British shoppers snapped up copies of a memoir by the ​brother of Princess Diana on Tuesday after their interest was piqued by incendiary allegations about her troubled marriage to ‌the now-king, including the claim he was "giddily elated" at her death.

Charles Spencer, who delivered a much-lauded eulogy at the 1997 funeral of his sister, has sparked global headlines with a book that accuses the then-Prince of Wales of sounding like a "lottery winner" in the hours after her death.

Buckingham Palace ​hit back immediately, saying the king was "mindful that the pain of fraternal grief can cloud reason, judgment and memory", ​as it sought to prevent the king from being dragged back into one of the royal ⁠family's most damaging periods.

The book, "Swan Song: Diana, My Sister", was released in Britain on Tuesday, where allegations contained ​in pre-released excerpts have dominated newspaper front pages for almost a week, helping send it straight to the top of the ​bestseller list on Amazon.

Spencer ⁠said he wrote the book to set the record straight and because it was his duty "as an eyewitness to history".

He said in the book that he spoke to Charles shortly after Diana's death was confirmed. "Unlike my other callers, who were stunned, barely able to articulate their condolences and offers of help, he sounded giddily elated – like a lottery winner, I remember thinking at the ​time," he wrote, according to pre-released ​excerpts.

"Looking back now, I ⁠suspect the prince's first reaction must have been to think more of how this event might free him to marry the woman he loved, rather than appreciating the loss of one he ​did not."

Spencer describes his book as an intimate, loving and honest portrait of his sister, who he said became a ​global icon overnight.