Joscelin de Louvain ^{1 2}

   Other names for Joscelin were Joscelin of Leuven, Joscelin de Lorraine, Joscelin "Barbatus" de Louvain, Joscelyn de Louvain, Joscelin de Louvain de Percy and Joscelyn Percy.

  Research Notes:

From Wikipedia - Joscelin of Leuven :

Joscelin of Leuven [1] (1121-1180) was a Brabantian nobleman who married an English heiress, Agnes de Percy , and settled in England. He took the name Percy.
He was given lands at Petworth , by William d'Aubigny, 1st Earl of Arundel . William had married Adeliza of Louvain , Joscelin's half-sister, and widow of Henry I of England .[2]

Family
He was a son of Godfrey I of Leuven and Clementia of Burgundy .
Joscelin and Agnes had at least seven children[3]:
Henry de Percy
Richard de Percy , (d.1244), who was a Magna Carta surety
Joscelin
Radulph, went to France
Eleanor
Maud (b. c. 1164), married John de Daiville [4]
Lucy
The Percy estate was divided between William, son of Henry, and Richard.

Joscelin married Agnes de Percy, daughter of William de Percy 4th Baron Percy and Alice de Clare, about 1154 in Egmanton, Nottinghamshire, England. (Agnes de Percy was born about 1134 in <Whitby>, Yorkshire, England and died about 1205.)