No chronicles tell of the duke's motive in joining the plot, although historian Charles Ross proposes that Buckingham was trying to distance himself from a king who was becoming increasingly unpopular with the people.
Ingen kronikører fortæller om hertugens motiv til at slutte sig til sammensværgelsen, selv foreslår historikeren Charles Ross at Buckingham forsøgte at distancere sig fra en kongen, som var blevet mere og mere upopulær hos folket.