There is a group of some fifteen letters all written by Gregory in the summer of 601 and arising in part from the more detailed information about the progress of the mission which some of Augustine's monks had brought back from England. We do not know when these monks went back to Rome and the fact of their journey can be established only from Gregory's references to it, not from any letters carried from England by the monks themselves. The great majority of the relevant letters written in 601 by Gregory were addressed to bishops in Gaul and in some instances his references to the English mission form no more than a closing paragraph in a letter otherwise concerned primarily with the affairs of the church in Gaul, and particularly with the synod whose calling he had previously urged but which had not yet met. Among the bishops to whom these letters were addressed we find, as in 596, the holders of the more southerly sees of the Rhône valley — Marseilles, Vienne and Lyons, as well as the metropolitan of Arles — but in addition we find also a group of more northerly sees — Toulon, Chalons-sur-Saône, Angers, Metz, Paris and Rouen.