Important role or Sir William Thornhill

Sir William Thornhill is uncle to Squire Thornhill. Initially introduced as a handsome and intelligent, though penniless young man, Mr. Burchell is eventually revealed to be a disguise behind which Sir William Thornhill hides. Through this disguise, he and Sophia fall in love, and marry after he reveals his true identity.

Sir William Thornhill's reputation rests on his having led a profligate youth but having reformed. Indeed, Burchell's virtue and wisdom - which is doubted by the Primrose family after they suspect him of sabotaging their plans to send the girls to town - make sense when he finally reveals his true identity.