Birthday celebrations for Princess Diana's family

The late princess was one of four siblings

Happy birthday to Charles Spencer, who is celebrating his 56th birthday. The younger brother of Princess Diana will be spending his special day at Althorp House, his family seat in the Northamptonshire countryside, along with his third wife Karen, and their seven-year-old daughter, Lady Charlotte Diana Spencer. Charles inherited the 90-room property upon the death of his father in 1992. It is famously the final resting place of his late sister. While his birthday celebrations will no doubt be muted, Charles can expect a number of calls and messages from his loved ones – not least from his six other children.

Charles Spencer at his 21st celebrations with his three sisters and Prince Charles

He shares four children with his first wife, Victoria Lockwood. The couple were married in September 1989, and together welcomed Lady Kitty Spencer, Lady Eliza Spencer, Lady Amelia Spencer, and Louis Spencer, Viscount Althorp, heir apparent to the earldom. They were divorced in 1997. In December 2001 he married Caroline Freud. They share two children together, The Hon Edmund Spencer and Lady Lara Spencer. Charles and Canadian philanthropist Karen tied the knot at Althorp in June 2011 – their daughter Charlotte Diana was born in July the following year.

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Speaking about his little girl's name, Charles previously said: "We hadn't settled on a first name before the birth, but Charlotte is a name we both love, and it really suits her. We knew that as soon as we saw her. And though it's been 15 years since Diana died, I still miss her every day and I wanted her commemorated in the naming of our daughter."

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Charles Spencer with his wife Karen

Charles also maintains a special relationship with his nephews, Prince William and Prince Harry, who will no doubt reach out on his special day. The royals have remained close to Charles and his two older sisters, Lady Sarah McCorquodale and Lady Jane Fellowes. All of Diana's siblings were at William and Kate’s wedding in 2011 where the hymns sung included Guide Me, O Thou Great Redeemer - the final hymn sung at Diana's funeral in 1997. William, who gave Kate his mother's sapphire and diamond engagement ring, and his bride had visited Diana's grave at Althorp days before the wedding.

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"The only downside on a perfect day was Diana not being there," Earl Spencer told the BBC after the 2011 nuptials. "It was incredibly beautiful wasn't it? Very moving," he added. "But what a wonderful day, such a celebration."

Princess Diana's funeral in September 1997

Harry is said to have kept the Spencers especially close. Notably, his maternal aunts and uncles were included by name in his son Archie's official birth announcement, which read, "The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, The Duke and Duchess of Cambridge, Lady Jane Fellowes, Lady Sarah McCorquodale and Earl Spencer have been informed and are delighted with the news."

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In his eulogy at Diana's funeral, Charles publicly vowed to look after his late sister's sons. "She would want us today to pledge ourselves to protecting her beloved boys William and Harry from a similar fate and I do this here, Diana, on your behalf," Spencer said in the speech. "We will not allow them to suffer the anguish that used to regularly to drive you to tearful despair."