On 28 October 1216, assisted by des Roches and at least four other bishops, the papal legate supervised the coronation of Henry III in the abbey church at Gloucester. The late king's regalia had been lost, or pawned to pay mercenaries, so that it was a chaplet or makeshift crown that des Roches placed on the head of the nine-year-old boy. Altogether the ceremony was something of a shambles, interrupted by protests from the abbot of Westminster and the prior of Christ Church Canterbury, and overshadowed by the news that only a few miles away the Welsh had set siege to Goodrich castle. Nonetheless, the coronation provides a remarkable illustration of des Roches' reconciliation with both church and baronage. Previously reviled by native and ecclesiastical opinion as an alien and secularist, he now found himself at the centre of resistance to a French invasion, a leading ally of the papal legate, personally investing his king with the attributes of sovereignty. Civil war had forged improbable alliances between native barons, alien courtiers and the representatives of the pope.

Prior to the death of King John, des Roches had been only one of several prominent courtiers whose obedience and loyalty to the crown had brought them status and wealth. After 1216, all of this changed. For the first time since the eleventh century, the king was a minor, incapable of governing in his own right. John's courtiers found themselves, in effect, no longer the servants but the masters of the court.