The Princess of Wales will no doubt be joining her sister, Pippa Middleton, in celebrating her nephew's fourth birthday on Saturday.
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Pippa and her husband James Matthews welcomed their first child, whose full name is Arthur Michael William Matthews, on 15 October 2018.
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The author and columnist gave birth on 15 October 2018 in the Lindo Wing of St Mary's Hospital in London – the same place where Kate welcomed all three of her royal children.
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No doubt the family and their relatives will be celebrating the little boy's birthday at the weekend or later during the week. Pippa and her older sister Kate are incredibly close and it's likely the Princess will have thought of a special gift for her four-year-old nephew.
Pippa, 39, is notoriously private about her family life, but in an interview in association with sportswear label Hoka One last year, the fitness fanatic revealed: "Being active with my 2.5-year-old son in the park or playground, transporting him on the back of my bike and buggy running when he was a baby have been ways in which I have been able to include outdoor exercise whilst being a hands-on mummy."
The Middleton sisters are extremely close
She added: "Being such an active family has rubbed off on my son, he loves nothing more than running wild in the woods, parks and fields with our two dogs, even if it’s howling a gale and pouring with rain."
Both Pippa and James are also doting parents to two other children, Grace, who turned one in March and four-month-old Rose.
While occasionally, Pippa used to be spotted with her children out and about in London, the mum-of-three and sister Kate have both relocated from the UK capital to the countryside.
Pippa has purchased a beautiful Georgian mansion in Berkshire while Princess Kate, along with her husband Prince William and their three children have moved to Adelaide Cottage in Windsor.