Hamelin was an illegitimate son of Geoffrey of Anjou born in approximately 1129, so half-brother of Henry II. He was married by order of the king to Isabella de Warenne, in her own right Countess of Surrey. She was the only surviving child of the third earl who’d died whilst he was on crusade. He first husband was the fourth earl. It just so happened that Isabelle’s husband was King Stephen’s son William of Blois – a real strategy to bring all that lovely land and loot into the family orbit. William must have been quite happy with the arrangement because he didn’t bat an eyelid when his father disinherits shim and made Henry Fitzempress, the son of his cousin Matilda, the heir to the throne and in so doing brought the years of anarchy and civil war to a conclusion. William who was several years younger than Isabel served Henry II until his death in 1159.
Henry II cast his eyes over all of Isabel’s considerable charms (that’ll be all those Yorkshire estates) and decided that they ought to be kept in the family. Enter Hamelin. After the marriage, in 1164, he was recognized as Earl of Warenne – or the fifth Earl of Surrey. Hamelin, unusually, took the name of his wealthy bride. Hamelin remained loyal throughout his life to his brother even though ultimately he did not agree with the end that befell Thomas Becket especially as he came to believe in the archbishop’s saintliness. He was supposed to have been cured of an eye problem by the cleric. He went with his niece Joan to Sicily when she married its king and his nephew, Richard the Lionheart, recognised his uncle’s trustworthiness when he became co-regent with William Longchamp whilst Richard was away on crusade and then found himself having to count the gold in order to ransom his nephew from the clutches of his enemies.
The de Warenne’s held lands across Yorkshire and it was Hamelin who built Conisborough Castle near Doncaster around about 1180.
His eldest son, William went on to marry William Marshal’s daughter Matilda who was at that time the widow of Hugh Bigod. One of Hamelin and Isabella’s daughter apparently got a little too close for comfort to her royal cousin Prince John, who had a reputation for liking the ladies, and bore him a child.