E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Henry, Lord Clifford, first Earl of Cumberland, and Lady Margaret Percy, his wife, are the originals of this ballad. Lord Clifford had a miserly father and ill-natured step-mother, so he left home and became the head of a band of robbers. The ballad was written in 1502, and says that the Not-browne Mayd was wooed and won by a knight who gave out that he was a banished man. After describing the hardships she would have to undergo if she married him, and finding her love true to the test, he revealed himself to be an earls son, with large hereditary estates in Westmoreland. (Percy: Reliques, series ii.)