Kirley Duke (born 1971) was the lead guitarist for the popular band The Weird Sisters.
Kirley was the son of Quidditch player Catriona McCormack and the brother of Meaghan McCormack. Both women played for the Pride of Portree.
The fact that both Kirley's mother and sister have the surname McCormack would seem to indicate that "Duke" is just a stage name.
Behind the scenes
Kirley Duke is portrayed by Jonny Greenwood in the film adaptation of Harry Potter and the Goblet of Fire