The succession to the throne is regulated not only through descent, but also by Parliamentary statute. The order of succession is the sequence of members of the Royal Family in the order in which they stand in line to the throne.
The basis for the succession was determined in the constitutional developments of the seventeenth century, which culminated in the Bill of Rights (1689) and the Act of Settlement (1701).
When James II fled the country in 1688, Parliament held that he had 'abdicated the government' and that the throne was vacant. The throne was then offered, not to James's young son, but to his daughter Mary and her husband William of Orange, as joint rulers.
It therefore came to be established not only that the Sovereign rules through Parliament, but that the succession to the throne can be regulated by Parliament, and that a Sovereign can be deprived of his title through misgovernment.
The succession to the throne is regulated not only through descent, but also by statute; the Act of Settlement confirmed that it was for Parliament to determine the title to the throne.
The Act laid down that only Protestant descendants of Princess Sophia - the Electress of Hanover and granddaughter of James I - are eligible to succeed. Subsequent Acts have confirmed this.
Parliament, under the Bill of Rights and the Act of Settlement, also laid down various conditions which the Sovereign must meet. A Roman Catholic is specifically excluded from succession to the throne; nor may the Sovereign marry a Roman Catholic.
The Sovereign must, in addition, be in communion with the Church of England and must swear to preserve the established Church of England and the established Church of Scotland. The Sovereign must also promise to uphold the Protestant succession.
THE LINE OF SUCCESSION
SOVEREIGN
1. The Prince of Wales
2. The Duke of Cambridge
3. Prince Henry of Wales
4. The Duke of York
5. Princess Beatrice of York
6. Princess Eugenie of York
7. The Earl of Wessex
8. Viscount Severn
9. The Lady Louise Mountbatten-Windsor
10. The Princess Royal
11. Mr. Peter Phillips
12. Miss Savannah Phillips
13. Mrs.Zara Tindall
14. Viscount Linley
15. The Hon. Charles Armstrong-Jones
16. The Hon. Margarita Armstrong-Jones
17. The Lady Sarah Chatto
18. Master Samuel Chatto
19. Master Arthur Chatto
20. The Duke of Gloucester
21. Earl of Ulster
22. Lord Culloden
23. The Lady Cosima Windsor
24. The Lady Davina Lewis
25. Miss Senna Lewis
26. The Lady Rose Gilman
27. Miss Lyla Gilman
28. The Duke of Kent
29. The Lady Amelia Windsor
30. The Lady Helen Taylor
31. Master Columbus Taylor
32. Master Cassius Taylor
33. Miss Eloise Taylor
34. Miss Estella Taylor
35. The Hon. Albert Windsor
36. The Hon. Leopold Windsor
37. The Lord Frederick Windsor
38. The Lady Gabriella Windsor
39. Princess Alexandra, the Hon. Lady Ogilvy