Premise: Henry Nevill, 6th and "de jure" 4th Baron Abergavenny KB (between 1527 and 153510 February 1587) was an English peer. He was the son of Sir George Nevill, 5th Baron Bergavenny, and Mary Stafford (daughter of Edward Stafford, 3rd Duke of Buckingham). He succeeded to the barony upon the death of his father, George Nevill, 5th Baron Bergavenny.
Hypothesis: Henry Nevill became a Duke later in life.