The Duke and Duchess of Edinburgh's daughter, Lady Louise Windsor, is celebrating her 20th birthday today (November 8th) and will no doubt be having a great day with her friends at the University of St Andrew's in Scotland.The royal is a popular member of the family who shared a particularly special bond with her late grandparents, the Queen and Prince Philip, thanks to her love of horses and carriage driving. As she enters her 20s, a leading royal expert has spoken to OK! about Lady Louise and why she is not only "a credit to her parents" but also how she has "nailed the art of being royal and relatable".