Queen Elizabeth II is the Queen of the United Kingdom and Head of the Commonwealth. She is currently played by Claire Foy. Beginning with Season 3, Olivia Colman will assume the role of the maturing Queen.
Born as the eldest child of the Duke and Duchess of York, she became the heir presumptive in 1936 when her uncle abdicated the throne and her father became King George VI. She ascended the throne in 1952 at the age of 25 following her father's untimely death.
In Wolferton Splash, November 1947, Elizabeth anxiously waits while her fiancée, Prince Philip of Greece and Denmark, surrenders his title as Prince of Greece and Denmark, and is named Philip, Duke of Edinburgh and Lieutenant of the Royal Navy so that he may be allowed to marry The Princess Elizabeth. The two marry in Westminster Abbey and four years later, have two young children, Charles and Anne, and are living in Malta where Philip has become Lieutenant-Commander in the Royal Navy.
News that Elizabeth's father, King George VI, has fallen ill calls the family back to London where George learns that he has a malignant lung tumor and has only months to live. However, Elizabeth, as well as her mother Queen Elizabeth, her sister Princess Margaret, and her paternal grandmother Queen Mary, are spared the truth. Elizabeth and Philip take up residence at Clarence House, where Philip eagerly oversees renovations. At breakfast with her mother and sister, Elizabeth observes the attraction between Margaret and her father's equerry, Group Captain Peter Townsend, but reminds Margaret that, although she understand the attraction, Peter is married and therefore unavailable.
On a Christmas trip to Sandringham, Elizabeth is alarmed at her father's sudden emotional breakdown while singing Christmas carols and furthermore when she realizes his hacking cough has not yet been repaired by surgery. Realizing Elizabeth will be Queen much sooner than expected, George makes an effort to prepare her for her role by asking that she and Philip take on the Commonwealth tour in his place, as he is too ill to travel. Philip at first heavily objects, not wishing to leave the children or his career for so long, but eventually agrees at his wife's insistence.
In Hyde Park Corner, Elizabeth and Philip begin the Commonwealth tour in Kenya, where they are eagerly greeted by the country's citizens. Their holiday begins on a happy note, as Philip and Elizabeth realize the convenience of being away from home without family or children. After courageously defending his wife from an elephant, Elizabeth promises Philip that she will write to her father asking if they may return to Malta, as she knows how he has missed their life there. That night, the two witness some spectacular nighttime wildlife and spend the rest of the evening together; unbeknownst to them, thousands of miles away, King George dies in his sleep at Sandringham after spending time with his wife and Margaret.
The next morning, Elizabeth and Philip depart once again, and seem lighthearted; Philip proudly looks on when Elizabeth makes use of her wartime experience as a mechanic, and Elizabeth writes a letter to her father. When word finally arrives in Kenya that the king has died, Elizabeth's personal secretary, Martin Charteris, rushes to get to Elizabeth and Philip before the press. Waking Philip from a nap, he informs the Duke of the news, and Philip insists he be the one to tell Elizabeth. Heartbroken at the tragic news of her father's death, Elizabeth and Philip leave Kenya, under the solemn note of the death of a sovereign.
On the plane, Elizabeth has trouble sleeping and apologizes to Philip for their happy trip having been cut short. She is even more saddened when she realizes her trusted secretary Martin is to be replaced by the former secretary of her father, Tommy Lascelles. Upon their arrival in London, Tommy insists Elizabeth walk in front of Philip, much to his subsequent irritation. At Buckingham Palace, Elizabeth goes to see her father one last time, and sobs at the sight of his lifeless body. But as she reunites with her mother, sister, and grandmother, she faces a much heavier task: becoming queen.