LONDON, ENGLAND - OCTOBER 20:  Catherine, Duchess of Cambridge, President of China Xi Jinping (C) and Britain's Queen Elizabeth II attend a state banquet at Buckingham Palace on October 20, 2015 in London, England. The President of the People's Republic of China, Mr Xi Jinping and his wife, Madame Peng Liyuan, are paying a State Visit to the United Kingdom as guests of the Queen. They will stay at Buckingham Palace and undertake engagements in London and Manchester. The last state visit paid by a Chinese President to the UK was Hu Jintao in 2005.  (Photo by Dominic Lipinski - WPA Pool /Getty Images)
LONDON, ENGLAND - OCTOBER 27:  HRH Queen Elizabeth II, Prince Philip, Duke of Edinburgh, Dr Devisingh Ramsingh Shekhawat and the President of the Republic of India Prathibha Devi Singh Patil arrive for a Banquet in Windsor Castle during the State Visit of the President on October 27, 2009 in London, England.  The President will stay at Windsor Castle as a guest of the Queen from Tuesday 27th October to Thursday 29th October.  (Photo by Chris Jackson - WPA Pool/Getty Images)
Britain s Queen Elizabeth II (right) and her husband, the Duke of Edinburgh (left) stand alongside Russia s President Putin and his wife, Lyudmila,  before a state banquet at Buckingham Palace, 24 June 2003. Earlier, Mr Putin, who is on the first state visit by a Russian leader since 1874 when Tsar Alexander II came to Britain, had been delayed by 15 minutes aftes his motorcade was delayed by heavy traffic as it travelled from London s Heathrow Airport to Horse Guards Parade for the official welcoming ceremony.   AFP  PHOTO Sean Dempsey. WPA Rota POOL  (Photo credit should read SEAN DEMPSEY/AFP/Getty Images)
LONDON, UNITED KINGDOM - DECEMBER 01:  Queen Elizabeth II And Prince Philip(right) With President Roh Moo-hyun Of South Korea And Mrs Roh Moo-hyun Before Attending A State Banquet At Buckingham Palace During Their State Visit.  (Photo by Tim Graham Picture Library/Getty Images)