Claim to the Throne
Lady Jane Grey was not simply chosen because of her fervent Protestantism, but because she had a legitimate claim to the throne, albeit a distant one compared to Mary and Elizabeth. As previously mentioned, Jane’s mother, Lady Frances, was the granddaughter of Henry VII (1457-1509), father of Henry VIII and founder of the whole Tudor Dynasty. This also meant that Henry VIII was her Lady Frances’s uncle. More tenuously, her father’s relation to the wife of Edward IV also gave her some further royal connections if not claims, given that Edward IV was of the defeated House of York.
Although her claim through lineage was not immutably strong, Jane did have the approval of the King himself, who was a popular figure and a boy expected to become a prudent ruler when he came of age. His treatment of Mary after the rebellion and plot to crown her at his expense suggested that, as well as having a fervent belief in the need for further reformation of the church, he was also prepared to show leniency. Power and alliances are also vital to any succession, and Jane had those, too, thanks to the oath Edward had the nobles swear.
Furthermore, the English Crown had previously been seized on flimsier pretexts. William I took the crown from Harold Godwineson in 1066 as he claimed that he had been verbally promised it by the childless Edward the Confessor. The very founder of the Tudor Dynasty, most recently, had also claimed the throne on a similar basis to Jane, despite what Tudor propaganda said. Henry VII’s claim was based on his grandmother, Catherine of Valois, being the widow of King Henry V and mother of King Henry VI, whose staggering incompetence as a ruler led to the Wars of the Roses.