Who is Henry Stafford, Duke of Buckingham from The Princes in the Tower and what is their importance?

Henry Stafford, Duke of Buckingham, was a prominent English nobleman with a claim in the line of succession. Married to Catherine Wydville, the Queen's sister, Henry became Richard of Gloucester's ally after the death of Edward IV. He then did everything possible to support Richard III...... up until the time Richard III shared his plan to kill the two princes. Gloucester's conscience did not allow for the boys' deaths, leading him to plot against Richard. As a result, he was arrested and executed.