The first four individuals in the line of succession who are over 21, and the sovereign's consort, may be appointed Counsellors of State. Counsellors of State perform some of the sovereign's duties in the United Kingdom while he or she is out of the country or temporarily incapacitated. Otherwise, individuals in the line of succession need not have specific legal or official roles.
The United Kingdom is one of the 16 Commonwealth realms. Each of those countries has the same person as monarch and the same order of succession. In 2011, the prime ministers of the realms agreed unanimously to adopt a common approach to amending the rules on the succession to their respective Crowns so that absolute primogeniture would apply for persons born after the date of the agreement, instead of male-preference primogeniture, and the ban on marriages to Roman Catholics would be lifted, but the monarch would still need to be in communion with the Church of England. After the necessary legislation had been enacted in accordance with each realm's constitution, the changes took effect on 26 March 2015.
No official, complete version of the line of succession is currently maintained. The exact number, in remoter collateral lines, of the people who would be eligible is uncertain. In 2001, American genealogist William Addams Reitwiesner compiled a list of 4,973 living descendants of the Electress Sophia in order of succession, but did so disregarding Roman Catholic status. When updated in January 2011, the number was 5,753.
The annotated list below covers the first part of this line of succession, being limited to descendants of the sons of George V, Elizabeth II's grandfather. The order of the first eighteen numbered in the list is given on the official website of the British Monarchy; other list numbers and exclusions are explained by annotations (Notes and sources below) and footnotes. People named in italics are unnumbered either because they are deceased or because sources report them to be excluded from the succession.