Piers Morgan has demanded that Earl Spencer's newly published memoir about Princess Diana be withdrawn from shelves after discovering a significant factual error regarding Morgan's role in publishing intrusive photographs of the princess at a gym in 1993. Earl Spencer mistakenly described Morgan as the editor of the Daily Mirror at the time, when Morgan was actually working at The Sun and only joined the Mirror as editor in 1995. Though Earl Spencer has apologised for the error, Morgan is pursuing legal action and has called for the offending pages to be removed or for the first edition to be pulped entirely.

The disputed photographs were published by the Sunday Mirror on 7 November 1993 and led to a 1995 settlement in which Mirror Group Newspapers reportedly paid Princess Diana's legal costs of approximately £1 million plus £200,000 to charities of her choice. Publisher Penguin has agreed to amend this single factual point in future editions of Swan Song: Diana, My Sister, released on 22 September. Morgan contends that as a historian, Earl Spencer should be particularly concerned with accuracy when discussing public figures in the historical record, and he is pursuing damages from both the author and publisher.