Queen Elizabeth II and Prince Philip, wearing the uniform of the Honorary Colonel-in-Chief of the Royal Canadian Regiment, pose for a portrait at Buckingham Palace before a Royal Tour, in London, Britain in 1959. Prince Philip, who was Queen Elizabeth's husband for more than seven decades and helped to modernise the British monarchy and steer the royal family through repeated crises, died on Friday. He was 99. Library and Archives Canada/National Film Board of Canada fonds/e010955850/Handout via REUTER

Prince Philip wears the uniform of the Honorary Colonel-in-Chief of the Royal Canadian Regiment as he poses for a portrait at Buckingham Palace, before a Royal Tour in London, Britain in 1959. The Duke of Edinburgh, as he was officially known, had been by his wife's side throughout her 69-year reign, the longest in British history. During that time he earned a reputation for a tough, no-nonsense attitude and a propensity for occasional gaffes. Library and Archives Canada/National Film Board of Canada fonds/e010975989/Handout via REUTERS.

Queen Elizabeth II and Prince Philip pose for a portrait at Buckingham Palace in London, Britain in 1952. Picture taken in 1952. Prince Charles, Philip and Elizabeth's eldest son and heir to the British throne, visited the queen at Windsor on Friday afternoon, a royal source said. Library and Archives Canada/National Film Board of Canada fonds/e010975988/Handout via REUTERS.

Queen Elizabeth II delivers an address to both houses of parliament at the Palace of Westminster May 5, 1995 watched by Prince Philip. REUTERS/File Photo

Britain's Queen Elizabeth and Prince Philip wait to greet guests prior to a state banquet at Bellevue presidential palace in Berlin, Germany June 24, 2015. REUTERS/Wolfgang Kumm/Pool/File Photo

Britain's Prince Philip, Duke of Edinburgh attends the Epsom Derby in Epsom, south of London, June 1, 2013. REUTERS/Andrew Winning/File Photo