WARSAW, POLAND - JULY 17: Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge with their children Prince George and Princess Charlotte arrive at Warsaw airport to start a 3 day tour on July 17, 2017 in Warsaw, Poland. (Photo by Arthur Edwards / Pool/ Getty Images)
The Duke and Duchess of Cambridge are seen arriving at the presidential palace in Warsaw for a breakfast meeting with Polish president Andrzej Duda and his wife Agata Kornhauser-Duda on 17 July, 2017. (Photo by Jaap Arriens/NurPhoto via Getty Images)
WARSAW, POLAND - JULY 17:  (NO UK SALES FOR 28 DAYS FROM CREATE DATE)  Catherine, Duchess of Cambridge meets well wishers during a visit with Prince William, Duke of Cambridge to the Presidential Palace  during an official visit to Poland and Germany on July 17, 2017 in Warsaw, Poland.  (Photo by Pool/Samir Hussein/Samir Hussein/WireImage)
WARSAW, POLAND - JULY 17:  (NO UK SALES FOR 28 DAYS FROM CREATE DATE) Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge with President of Poland Andrzej Duda and the first Lady Agata Kornhauser-Duda attend the Queen's Birthday Garden Party at the Orangeryeduring an official visit to Poland and Germany on July 17, 2017 in Warsaw, Poland.  (Photo by Pool/Samir Hussein/Samir Hussein/WireImage)
WARSAW, POLAND - JULY 17:  (NO UK SALES FOR 28 DAYS FROM CREATE DATE) Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge  attend the Queen's Birthday Garden Party at the Orangeryeduring an official visit to Poland and Germany on July 17, 2017 in Warsaw, Poland.  (Photo by Pool/Samir Hussein/Samir Hussein/WireImage)