BERLIN, GERMANY - JULY 19: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg. (Photo by Matthias Nareyek - Pool/Getty Images)
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BERLIN, GERMANY - JULY 19: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend The Queen's Birthday Party at the British Ambassadorial Residence during an official visit to Poland and Germany on July 19, 2017 in Berlin, Germany. (Photo by Chris Jackson - Pool/Getty Images)
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BERLIN, GERMANY - JULY 19: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge attend The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg. (Photo by Matthias Nareyek - Pool/Getty Images)
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Getty Images Entertainment Matthias Nareyek

BERLIN, GERMANY - JULY 19: Catherine, Duchess of Cambridge attends The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg. (Photo by Matthias Nareyek - Pool/Getty Images)
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Getty Images Entertainment Matthias Nareyek

BERLIN, GERMANY - JULY 19: Catherine, Duchess of Cambridge attends The Queen's Birthday Party at the British Ambassadorial Residence on the first day of their visit to Germany on July 19, 2017 in Berlin, Germany. The royal couple are on a three-day trip to Germany that includes visits to Berlin, Hamburg and Heidelberg. (Photo by Matthias Nareyek - Pool/Getty Images)
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Getty Images Entertainment Matthias Nareyek