From a history of Brecon Castle:70
The careers of the two last Dukes of Buckingham illustrate this vividly. Henry Stafford. the second duke, had been a supporter of Richard III but they had fallen out and Henry retired to his castle at Brecon. Here he plotted against the King. His accomplice was a prisoner at the castle, John Morton, Bishop of Ely. (After whom the Ely Tower and Ely place are named.) The duke raised an army to oppose the King but his rebellion failed and he was executed. The bishop fled abroad and joined the Earl of Richmond who was soon to defeat Richard III at Bosworth and to become the first Tudor monarch, Henry VII. The King employed the bishop as one of his most efficient tax collectors; he was the Morton of Morton's fork. The new King also rewarded the Stafford family for their loyalty. Edward, born in Brecon castle in February 1478, was granted all the honours, titles and lands which had belonged to his father. However the second Tudor found it necessary to execute this the third and last duke. In 1521 Buckingham very rashly flaunted his royal connections and claim to the throne. At the time, when Henry VIII had no legitimate heir.