Answer:
Elizabeth II ascended to the thrones of the Commonwealth Realms on February 6, 1952, at age 25, upon the death of her father, King George VI. She was crowned as Queen of the United Kingdom, Canada, Australia, New Zealand and Her Other Realms and Territories on June 2, 1953.
Note:
Elizabeth II is not - and never has been - Queen of England; that title has not existed for over 300 years.
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