British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

British Prime Minister Theresa May and Belgian counterpart Charles Michel attend a wreath-laying ceremony at the graves of John Parr and George Ellison, the first and the last British soldiers killed in the First World War, during celebrations marking the 100th anniversary of the end of the First World War, at the Saint Symphorien Military Cemetery in Mons, Belgium November 9, 2018. Benoit Doppagne/Pool via REUTERS 

Children react after competing in a pedal car race as motoring enthusiasts attend the Goodwood Revival, a three-day classic car racing festival celebrating the mid-20th century heyday of the sport, at Goodwood in southern Britain, September 9, 2018. REUTERS/Toby Melville TPX IMAGES OF THE DAY 

A woman takes a picture of herself inside a reinterpretation of Spanish artist Salvador Dali's "The Mae West Room" during a media presentation of the exhibition "Duchamp, Magritte, Dali: Revolutionary artists from the 20th century" in Madrid, Spain, April 9, 2018. REUTERS/Susana Vera 

Former President Barack Obama visits the 9th-century Borobudur Temple in Magelang, Central Java, Indonesia June 28, 2017. REUTERS/Pius Erlangga 

Former President Barack Obama (C) waves while walking with his daughter Malia during a visit to the 9th-century Borobudur Temple in Magelang, Central Java, Indonesia June 28, 2017. REUTERS/Pius Erlangga 

Former U.S. President Barack Obama visits the 9th-century Borobudur Temple in Magelang, Central Java, Indonesia June 28, 2017. REUTERS/Pius Erlangga 

Former U.S. President Barack Obama waves while walking with his daughter Mali and his wife Michelle during a visit to the 9th-century Borobudur Temple in Magelang, Indonesia June 28, 2017. REUTERS/Pius Erlangga 

Former U.S. President Barack Obama (C) along with his daughters Malia (2-L) and Sasha (3-L) and his wife Michelle (L, hidden) visit the 9th-century Borobudur Temple in Magelang, Indonesia June 28, 2017. REUTERS/Pius Erlangga 

Canadian Governor General David Johnston followed by Canadian Prime Minister Justin Trudeau shake hands with members of the Canadian delegation at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales, followed by Canadian Governor General David Johnston greet members of the Canadian delegation at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales, followed by Canadian Governor General David Johnston shake hands with members of the Canadian delegation at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau (L) shakes hands with a veteran at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

People sit at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales, shakes hands with a war veteran at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau shakes hands with people at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

The crowd gathes at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

French President Francois Hollande (4th L), Canadian Prime Minister Justin Trudeau (3rd L), his wife Sophie Gregoire (L) and son Xavier (2ndL), Britain's Charles, Prince of Wales (4th R), Governor General of Canada David Johnston (C), his wife Sharon (3rd R) Britain's Prince William (2nd R), Duke of Cambridge and Britain's Prince Harry (R) pose at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Prince Charles (C) and Canadian Governor-General David Johnston lay wreaths at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales (2nd L), Governor General of Canada David Johnston (C), his wife Sharon (2nd R) Britain's Prince William, Duke of Cambridge (2nd L) and Britain's Prince Harry (L) visit the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

French President Francois Hollande (L), French Minister for Cities, Youth and Sport Patrick Kanner (2nd L) Canadian Prime Minister Justin Trudeau (R), his wife Sophie Gregoire and son Xavier visit the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

War veterans and members of the Canadian delegation salute at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau pay their respects as they attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

War veterans and members of the Canadian delegation salute at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

(From R) French President Francois Hollande, Canadian Prime Minister Justin Trudeau, his wife Sophie Gregoire and son Xavier attend a ceremony marking the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Vimy Memorial, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau speaks with a child at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau and French President Francois Hollande (R) arrive to lay wreaths at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau shake hands as they attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

Singer Isabelle Boulay performs during a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann

Singer Isabelle Boulay performs during a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann

Britain's Prince William looks to the crowd at the end of the ceremony to commemorate the 100th anniversary of the battle of Vimy Ridge, at Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Pascal Rossignol 

Britain's Prince William interacts with the crowd at the end of the ceremony to commemorate the 100th anniversary of the battle of Vimy Ridge, at Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Pascal Rossignol 

Canadian Prime Minister Justin Trudeau interacts with the crowd at the end of the ceremony to commemorate the 100th anniversary of the battle of Vimy Ridge, at Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Pascal Rossignol 

Soldiers and the Royal Canadian Mounted Police stand next to boots sitting on the lawn, during a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Soldiers stand next to boots sitting on the lawn, during a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau shake hands as they attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

Canadian Prime Minister Justin Trudeau (L) and French President Francois Hollande lay wreaths at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau lays a wreath at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Prince Charles (L) and Canadian Governor-General David Johnston attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann

Boots with red poppies sit on the lawn during a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau interacts at the end of the ceremony to commemorate the 100th anniversary of the battle of Vimy Ridge, at Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Pascal Rossignol 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau shake hands as they attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau shake hands as they attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

Boots with red poppies sit on the lawn during a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

A sculpture of red poppies by artist Bernard Freseau and boots are displayed at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Soldiers walk past boots sitting on the lawn during a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales (4thR), Britain's Prince William, Duke of Cambridge (3rdR), Britain's Prince Harry (2ndR), Governor General of Canada David Johnston (6thR), his Wife Sharon Johnston (5thR) French President Francois Hollande (5thL), Canadian Prime Minister Justin Trudeau (4thL), his wife Sophie Gregoire (3rdL) and their son Xavier (2ndL), French Junior Minister for Veterans Jean-Marc Todeschini (L), and former governor general of Canada Adrienne Clarkson (R) attend a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Canadian Prime Minister Justin Trudeau (L) his wife Sophie Gregoire (C) and son Xavier (R) visit the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Charles, Prince of Wales (R), Governor General of Canada David Johnston (2nd R), Britain's Prince William, Duke of Cambridge (2nd L) and Britain's Prince Harry visit the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

A serviceman bows his head near boots and poppies during a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann

Britain's Prince William, Duke of Cambridge lays red poppies, at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

(LtoR) Britain's Charles, Prince of Wales, Britain's Prince William, Duke of Cambridge and Britain's Prince Harry, attend a commemoration ceremony at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

Britain's Prince Harry lays red poppies, at the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL 

A photograph sits on the Tomb of the Unknown Soldier following a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the National War Memorial in Ottawa, Ontario, Canada, April 9, 2017. REUTERS/Chris Wattie 

French President Francois Hollande (L) and Canadian Prime Minister Justin Trudeau attend a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the Canadian National Memorial in Vimy, France, April 9, 2017. REUTERS/Christian Hartmann 

Photographs and a poppy sit on the Tomb of the Unknown Soldier following a ceremony to commemorate the 100th anniversary of the Battle of Vimy Ridge at the National War Memorial in Ottawa, Ontario, Canada, April 9, 2017. REUTERS/Chris Wattie