Britain's Catherine, Duchess of Cambridge smiles as she arrives with Belgian Countess and wife of Hereditary Grand-Duke of Luxembourg Stephanie de Lannoy (R) during the Celebration of the 150th anniversary of the 1867 Treaty of London in Luxembourg, on May 11, 2017. / AFP PHOTO / JOHN THYS (Photo credit should read JOHN THYS/AFP via Getty Images)
Crown Princess Stephanie arriving at MUDAM (Musze d'Art Moderne) for a visit with the Duchess of Cambridge during a day of visits in Luxembourg where she is attending commemorations marking the 150th anniversary 1867 Treaty of London, that confirmed the country's independence and neutrality. (Photo by Dominic Lipinski/PA Images via Getty Images)
The Duchess of Cambridge is given some flowers as she arrives with Crown Princess Stephanie at MUDAM (Musze d'Art Moderne) during a day of visits in Luxembourg where she is attending commemorations marking the 150th anniversary 1867 Treaty of London, that confirmed the country's independence and neutrality. (Photo by Dominic Lipinski/PA Images via Getty Images)
LUXEMBOURG - MAY 11: Catherine, Duchess of Cambridge (C) poses with (L-R) Princess Stephanie of Luxembourg, Henri, Grand Duke of Luxembourg, Maria Teresa, Grand Duchess of Luxembourg and Prince Guillaume of Luxembourg during a visit to the Grand Ducal Palace on May 11, 2017 in Luxembourg. The Duchess is participating in the official commemoration of the 1867 Treaty of London and will attend a series of engagements to celebrate the cultural and historic ties between the UK and Luxembourg. (Photo by Samir Hussein/WireImage)
The Duchess of Cambridge joins the Luxembourg Prime minister Xavier Bettel (left), Princess Stephanie and Crown Prince Guillaume for a walkabout during a day of visits in Luxembourg where she is attending commemorations marking the 150th anniversary 1867 Treaty of London, that confirmed the country's independence and neutrality. (Photo by Dominic Lipinski/PA Images via Getty Images)
