A note on the 8th master of theology
When Raoul de Namur was sent as a spy against the Amalricians, he was given his authorisation, according to Caesarius von Heisterbach, by the Bishop of Paris and three masters of theology there who were named as Decanum Salebergiensem et magistrum Robertum de Kortui et magistrum Stephanum. Robert de Kortui must be Robert de Courçon, and Stephanus must refer to Etienne de Reims: both are known to have been masters of theology at Paris at the time.
This leaves the problematical Decanus Salebergiensis. Two pairs of translators, Wakefield and Evans, and Scott and Bland, have translated this as the Dean of Salzburg (decanus Salisburgensis); but no such figure was teaching theology in Paris at the time. Nor was any dean from Strasbourg, to support the reading given, for no clear reason, by the historians, Paul Alphandéry and Henri Maisonneuve. The earlier historian, B. Hauréau, thought that it referred to a Dean of Salisbury (decanus Salisberiensis), which he took to be a reference to Richard Poore.
After Pope Innocent III’s intervention in 1207, there could only be 8 masters of theology teaching in Paris at any one time. P. Glorieux, the historian who has made a study of them, was sure of the identity of 6 of them for the period 1209-10: namely, Prévostin, Etienne de Reims, Jean de la Chandeleur, Robert de Courçon, Pierre de Capoue (or de Mora) and Jean Halgrin; and he had good reasons for thinking that Jacques d’Arras was the seventh. The supposition that he made, that the eighth master was Thomas Gallus, canon of Saint-Victor, was only speculation.
If Thomas Gallus had not yet become a master of theology, he could well be the Brother Thomas who also figures in the story of the capture of the Amalricians. The first to give help to Raoul de Namur were Prior Jean le Teutonique, Brother Thomas and Master Robert, all of Saint-Victor, which was orchestrating the anti-Amalrician campaign. Master Robert was Robert of Flamborough, who had been a colleague of Robert de Courçon as a papal investigator from 1205-7. He was writing his manual for confessors, the Penitentiale, at Saint-Victor at some time between 1208 and 1213. However, whether Brother Thomas was Thomas Gallus is not known. Thomas Gallus was at Saint-Victor until at least 1219.
A dean of Salisbury was certainly teaching theology at Paris in 1213, when Pope Innocent III wrote to him, addressing him as Decanus Sereberiensis docens Parisius sacram paginam (currently teaching theology at Paris) and gave him the task of investigating Gautier de Mussy. It may be relevant that Gautier was linked, by the Anonymous of Laon, with the Amalricians. This master of theology in 1213 was Thomas of Chobham, who was a dean, or sub-dean, of Salisbury. He had become sub-dean of Salisbury between 1206 and 1208. There is a gap in his career in England, during a time of friction between King John and the Church, from 1208 to 1213. It is reasonable to assume that he spent most of this period teaching theology in Paris.
I therefore suggest that the eighth master of theology in 1209/10 is likely to have been Thomas of Chobham, who was a sub-dean (or had he by then been made up to dean?) of Salisbury; and that the German chronicler, Caesarius, unaware of Salisbury, confused it with Salzburg, to produce this problematical decanus Salebergiensis.