Gilbert was born at Sempringham, near Bourne in Lincolnshire, the son of Jocelin, an Anglo-Norman lord of the manor, who unusually for that period, actively prevented his son from becoming a knight, instead sending him to the University of Paris to study theology.
It is not clear why Jocelin sought confirmation of ownership, since the bishopric had possessed the land of "Conglud", that is, Kinclaith (modern Glasgow Green) since the reign of King Máel Coluim IV.