LONDON, ENGLAND - DECEMBER 19: Catherine, Duchess of Cambridge attends a Christmas party for volunteers at The Mix youth service on December 19, 2016 in London, England. The Mix youth service works with Their Royal Highnesses' Heads Together Campaign. (Photo by Samir Hussein/WireImage)
LONDON, ENGLAND - DECEMBER 19: Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge with Prince Harry attend a Christmas party for volunteers at The Mix youth service on December 19, 2016 in London, England. The Mix youth service works with Their Royal Highnesses' Heads Together Campaign. (Photo by Chris Jackson/Getty Images)
LONDON, ENGLAND - DECEMBER 19: Catherine, Duchess of Cambridge arrives to attend a Christmas party for volunteers at The Mix youth service on December 19, 2016 in London, England. The Mix youth service works with Their Royal Highnesses' Heads Together Campaign. (Photo by Chris Jackson/Getty Images)
LONDON, ENGLAND - DECEMBER 19: Catherine, Duchess of Cambridge smiles as he talks to staff and young people during a visit to a Christmas party for volunteers at The Mix youth service on December 19, 2016 in London, England. The Mix youth service works with Their Royal Highnesses' Heads Together Campaign. (Photo by Alastair Grant - WPA Pool/Getty Images)
LONDON, ENGLAND - DECEMBER 19: Catherine, Duchess of Cambridge attends a Christmas party for volunteers at The Mix youth service on December 19, 2016 in London, England. The Mix youth service works with Their Royal Highnesses' Heads Together Campaign. (Photo by Samir Hussein/WireImage)
