In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.

Elizabeth II (Elizabeth Alexandra Mary; born 21 April 1926) has been Queen of the United Kingdom, Canada, Australia, and New Zealand since 6 February 1952. Additionally, she is Head of the Commonwealth and queen of 12 countries that have become independent since her accession: Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines, Belize, Antigua and Barbuda, and Saint Kitts and Nevis.
how old was the queen when she became queen of england