Spencer said he decided to write after receiving repeated interview requests ahead of the 30th anniversary of Diana’s death.
He said: “With the 30th anniversary of Diana’s tragic death on the skyline (next year), I’ve been inundated yet again with requests for interviews about my sister. This has convinced me to write down my own thoughts and memories, once and for all, rather than having the discomfort of again reading the opinions of others, many of which are based on untruths that have become accepted over time.”
Spencer added his Swan Song book aims to “tell the truth about Diana from her brother’s perspective, just as I attempted to do when speaking at her funeral.”
He added: “As with my eulogy, I want to speak on Diana’s behalf and do so in an openly positive way.”
At Diana’s 1997 funeral, Spencer made an emotional pledge concerning her sons, Prince William, now 44, and Prince Harry, 41.
He said: ‘I pledge that we, your blood family, will do all we can to continue the imaginative