I've found a reference to it from John Paddy Brown's folk songs of Old Hampshire and its described: The Monmouth Rebel gives the story of a fictional supporter of the Monmouth Rebellion, who gets pardoned for his part in the doomed rising (against King James 2cd). However, the pardoned rebel's fiancé is less fortunate, being condemned by Judge Jeffries (of the Bloody Assizes notoriety) when she is found guilty of hiding known rebels who were being treated as outlaws. She is sent for execution, leaving the live, free rebel alone and dejected in the World.