Who were the parents of the King with a mistress named Rosamund Clifford?
Fair Rosamond (opera): Fair Rosamond is an English historical opera in four acts composed by John Barnett, written in 1837 to a libretto by Charles Zachary Barnett, after the legend of Rosamund Clifford ("Fair Rosamond" or the "Rose of the World"), the 12th century mistress of King Henry II who was said to have been poisoned by the King's wife, Queen Eleanor. Henry II of England:  Henry was the son of Geoffrey of Anjou and Matilda, daughter of Henry I of England.
Geoffrey of Anjou and Matilda