LONDON, ENGLAND - MARCH 14: Queen Elizabeth II (left) is presented with Letters of Credence by Her Excellency the Ambassador of the Democratic Republic of the Congo, Marie Ndjeka Opombo, during a private audience with Her Majesty on March 14, 2017 at Buckingham Palace, London, England. (Photo by Steve Parsons - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 14: Queen Elizabeth II (left) is presented with Letters of Credence by Her Excellency the Ambassador of the Democratic Republic of the Congo, Marie Ndjeka Opombo, during a private audience with Her Majesty on March 14, 2017 at Buckingham Palace, London, England.  (Photo by Steve Parsons - WPA Pool/Getty Images)

LONDON, ENGLAND - JUNE 1: Queen Elizabeth II is greeted in the traditional style by the the High Commissioner of Fiji, Mr Jitoko Tikolevu, as he presents his credentials during a private audience also attended by his wife, Mrs Luisa Tikolevu, at Buckingham Palace on June 1, 2016 in London, England. (Photo by John Stillwell - WPA Pool/Getty Images)

LONDON, ENGLAND - JUNE 1: Queen Elizabeth II is greeted in the traditional style by the the High Commissioner of Fiji, Mr Jitoko Tikolevu, as he presents his credentials during a private audience also attended by his wife, Mrs Luisa Tikolevu, at Buckingham Palace on June 1, 2016 in London, England. (Photo  by John Stillwell - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 14: Queen Elizabeth II is presented with Letters of Credence by His Excellency the Ambassador of Spain Carlos Bastarreche, during a private audience with Her Majesty on March 14, 2017 at Buckingham Palace, London, England. (Photo by Steve Parsons - WPA Pool/Getty Images)

LONDON, ENGLAND - MARCH 14: Queen Elizabeth II is presented with Letters of Credence by His Excellency the Ambassador of Spain Carlos Bastarreche, during a private audience with Her Majesty on March 14, 2017 at Buckingham Palace, London, England.  (Photo by Steve Parsons - WPA Pool/Getty Images)

LONDON, ENGLAND - NOVEMBER 22: Queen Elizabeth II with Ambassador of the Republic of Albania in the UK Qirjako Qirko as he presents his Letters of Credence during an audience at Buckingham Palace on November 22, 2016 in London, England. (Photo by Yui Mok - WPA Pool/Getty Images)

LONDON, ENGLAND - NOVEMBER 22:  Queen Elizabeth II with Ambassador of the Republic of Albania in the UK Qirjako Qirko as he presents his Letters of Credence during an audience at Buckingham Palace on November 22, 2016 in London, England.  (Photo by Yui Mok - WPA Pool/Getty Images)

LONDON, UNITED KINGDOM - FEBRUARY 16: Queen Elizabeth II shakes hands with His Excellency George Aboua, the High Commissioner of the Cote d'Ivoire, before he presented his Letters of Credence during a private audience at Buckingham Palace on February 16, 2015 in London, England. (Photo by Jonathan Brady - WPA Pool/Getty Images)

LONDON, UNITED KINGDOM - FEBRUARY 16: Queen Elizabeth II shakes hands with His Excellency George Aboua, the High Commissioner of the Cote d'Ivoire, before he presented his Letters of Credence during a private audience at Buckingham Palace on February 16, 2015 in London, England. (Photo by Jonathan Brady - WPA Pool/Getty Images)