Claim: Elizabeth II has witnessed big constitutional changes.

Elizabeth II -LRB- Elizabeth Alexandra Mary ; born 21 April 1926 -RRB- has been Queen of the United Kingdom , Canada , Australia , and New Zealand since 6 February 1952 . 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 .   Elizabeth was born in London as the elder child of the Duke and Duchess of York , later King George VI and Queen Elizabeth , and she was educated privately at home . Her father acceded to the throne on the abdication of his brother Edward VIII in 1936 , from which time she was the heir presumptive . She began to undertake public duties during the Second World War , serving in the Auxiliary Territorial Service . In 1947 , she married Philip , Duke of Edinburgh , a former prince of Greece and Denmark , with whom she has four children : Charles , Prince of Wales ; Anne , Princess Royal ; Prince Andrew , Duke of York ; and Prince Edward , Earl of Wessex .   Elizabeth 's many historic visits and meetings include a state visit to the Republic of Ireland and visits to or from five popes . She has seen major constitutional changes , such as devolution in the United Kingdom , Canadian patriation , and the decolonisation of Africa . She has reigned through various wars and conflicts involving many of her realms . She is the world 's oldest reigning monarch as well as Britain 's longest-lived . In 2015 , she surpassed the reign of her great-great-grandmother , Queen Victoria , to become the longest-reigning British monarch and the longest-reigning queen regnant and female head of state in world history . In October 2016 , she became the longest currently reigning monarch and head of state following the death of King Bhumibol Adulyadej of Thailand .   Times of personal significance have included the births and marriages of her children , her coronation in 1953 , and the celebration of milestones such as her Silver , Golden , and Diamond Jubilees in 1977 , 2002 , and 2012 , respectively . In 2017 she became the first British monarch to commemorate a Sapphire Jubilee . Moments of sadness for her include the death of her father in 1952 at age 56 ; the assassination of Prince Philip 's uncle Lord Mountbatten in 1979 ; the breakdown of her children 's marriages in 1992 -LRB- her annus horribilis -RRB- ; the death in 1997 of her son 's former wife , Diana , Princess of Wales ; and the deaths of her mother and sister in 2002 . Elizabeth has occasionally faced republican sentiments and press criticism of the royal family ; however , support for the monarchy remains high , as does her personal popularity .