Margaret Tudor, sister of King Henry VIII of England, marries King James IV of Scotland. This marriage establishes a Stuart claim to the English throne, as their descendants would be in the line of succession.

Henry VIII marries Anne Boleyn, leading to the English Reformation. This is significant because Henry's subsequent annulments and marriages, and the legitimacy of his heirs, become contested, impacting the line of succession.

Edward VI, son of Henry VIII and Jane Seymour, ascends the English throne. However, he dies young without an heir.

Lady Jane Grey is briefly proclaimed Queen of England following Edward VI's death, but she is quickly deposed by Mary Tudor.

Mary Tudor, daughter of Henry VIII and Catherine of Aragon, becomes Queen of England. She is a Catholic, and her reign is marked by religious persecution of Protestants.

Elizabeth I, daughter of Henry VIII and Anne Boleyn, becomes Queen of England. Catholics, however, did not recognise her as legitimate because they did not recognise Henry's divorce from Catherine of Aragon, and hence his marriage to Anne Boleyn. Mary, Queen of Scots, as the great-granddaughter of Henry VII, was therefore seen as the legitimate heir to the English throne by many Catholics.

Mary's arrival in England further complicates the English succession. Catholic factions in England see her as the rightful queen, posing a direct threat to Elizabeth I.

Throughout her imprisonment, Mary remains a focal point of English succession politics. Numerous plots and conspiracies involve her, fueled by her claim to the throne and the desire of some Catholics to replace Elizabeth.