Princess Diana's brother Charles Spencer and wife Karen divorcing after 13 years of marriage

The 9th Earl Spencer and younger brother of the late Princess Diana announced the split to The Mail on Sunday.

He told the outlet: "It is immensely sad.

"I just want to devote myself to all my children, and to my grandchildren, and I wish Karen every happiness in the future."

Spencer's relationship with Karen, 52, came to an end amid writing his memoir, A Very Private School.

The former couple announced their split to the staff at Althorp House, Charles’s ancestral home, in April.

The earl is understood to be "becoming close to" Norwegian archaeologist Dr Cat Jarman, who co-hosts the history podcast The Rabbit Hole Detectives with Spencer and Reverend Richard Coles.

The outlet reported that they "look very happy together but that it is early days".

The Earl and Countess of Spencer married on June 18, 2011, at Althorp House.

The wedding took place just two months after Spencer’s nephew Prince William married Princess Kate.

The historic English estate, where Spencer and his sister Diana grew up, became Karen's residence upon their marriage.

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The earl and countess share a 12-year-old daughter, Charlotte Diana, whose middle name pays tribute to the former Princess of Wales.

Karen also has two older daughters from her previous marriage to Hollywood producer Mark Gordon.

The Earl Spencer has four children with his first wife, Victoria Lockwood, and two children with his second wife, Caroline Freud.