The Princess of Wales celebrated her special day on Monday 9 January
The Princess of Wales celebrated her 41st birthday on Monday, and the special day actually signified a new milestone for Kate.
The former Duchess of Cambridge marked her first birthday with her new royal title - Her Royal Highness The Princess of Wales.
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On 9 September, following Queen Elizabeth II's death, King Charles announced the appointment of Prince William as Prince of Wales, with Kate becoming Princess of Wales.
The title was previously held by William's late mother, Princess Diana. The courtesy title has been used for centuries and is typically held by the wife of the heir to the British throne.
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The Waleses on Christmas Day
Royal sources previously told HELLO! that Kate, in particular, "appreciates the history associated with this role but will understandably want to look to the future as she creates her own path".
Kate celebrated her birthday privately with William and their three children, but the royal couple are expected to return to royal duties this week, following their Christmas break in Norfolk.
The Waleses attended the Christmas Day church service in Sandringham alongside King Charles and Queen Consort Camilla, as well as extended members of the royal family.
During the holidays, the family-of-five also enjoyed a trip to see Santa at Lapland UK and William even reportedly treated his wife to a thrilling date by taking an Aston Martin DBX707 for a weekend test drive.
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