On July 19, 1553, the "Nine Days Queen" lost her throne. Mary Tudor had thwarted Northumberland's attempt to change the succession and insure the continuation of Edward VI's Calvinist Reformation in England. Although usually called Lady Jane Grey, I believe that since the young, militant Protestant had married Northumberland's younger son she should be known as queen by her married name.
Leanda de Lisle published a splendid study of the three Grey sisters and their respective claims on the throne of England--and what those claims cost them. The title is a little bit of a misnomer, as two of the three Grey sisters had no desire to be Queen of England at all, but I learned a lot from The Sisters Who Would be Queen: Mary, Katherine, and Lady Jane Grey: A Tudor Tragedy and reviewed it favorably on amazon.com:
Along with her first book: "After Elizabeth" (and its very long subtitle), Leanda de Lisle has written this book, focused on the Grey sisters to explore the complex issues of succession in the Tudor Dynasty. After all, so many of Henry VIII's decisions and actions were all directed at ensuring orderly succession after his death. When the only surviving child of his marriage to Catherine of Aragon was a daughter, he feared rebellion and civil war if Mary succeeded him. Therefore, he turned heaven and earth upside down to marry Anne Boleyn, young and promising a son, separating England from the universal Catholic Church and the authority of the Pope, risking war with the Holy Roman Empire, and incurring excommunication. Once he had his son (having to get rid of another disappointing wife), he then violated the principle of primogeniture and settled the succession, with Parliament's consent on the heirs of, not his eldest sister, Margaret, but his favorite sister Mary: the Greys, who would follow his son and daughters if they died without issue.
Ironically, this left only women to succeed Edward VI if he died without issue: his sisters Mary and Elizabeth and their relatives Frances, Jane, Katherine and Mary.
Then both Edward VI and Elizabeth I contravened Henry's will: Edward by naming Jane Grey his heir and Elizabeth by naming Mary, Queen of Scots as hers. (Mary I regretted the inevitability of Elizabeth's succession but did not try to thwart it.) Edward made his decision based on religious principle, since Jane was an Evangelical like him. Elizabeth made her decision based on primogeniture and Mary's royal person, since Mary, Queen of Scots, after all, was a Catholic--and many in her court dreaded another queen and a Catholic on the throne.
Leanda de Lisle traces this sometimes confusing web of succession, with the plots of attempted coups and subterfuges of secret marriages as clearly as possible (with name changes and so many Mary's and Catherine's). She corrects many erroneous interpretations (of Lady Jane Grey as victim or of her mother Frances as an evil woman, etc) effectively, and demonstrates Elizabeth I's cruelty to Katherine and Mary, imprisoning and separating them from their well-beloved husbands and Katherine from one of her sons. The book is very well illustrated too, with excellent family trees for the Tudors and the Greys, et al. One irony of the family trees in my copy was that Jane's name was nearly always in the gutter of the spread!
Mary Tudor, Renaissance Queen, told the story of Lady Jane Dudley and Mary Tudor in daily installments last year. I've linked the post about Jane's fall and Mary's triumph.