Gerard was possibly born in England, taught canon law[a] at the University of Paris in the 1150s, when the study of the discipline of the Church was first differentiated from theology, spurred by the collections of church decretals that began with the Decretum Gratiani assembled by a monk at the University of Bologna.
Among his pupils were Lucas of Hungary, Ralph Niger, master Richard, a certain Gervase who retired to Durham, and the English scholar Walter Map.
[2] Gerard was a member of Thomas Becket's entourage, his extended familia,[3] and a close friend of John of Salisbury.
[4] After Becket went into exile, Gerard taught for a while in Paris before he undertook a mission to the Empire[5] in 1165/66 even though Frederick Barbarossa was under a ban of excommunication.
[7] From about 1174 Gerard was once again in England, serving as a principal clerk to Becket's successor as Archbishop of Canterbury, Richard of Dover.