Work on the building's west façade continued under the bishopric of Monseigneur Guillaume Pinchon from his arrival in 1220 to his exile to Poitiers in 1228 following Pinchon's conflict with Pierre Mauclerc. When he returned in 1231, he had a chapel built on the south side of the building, this dedicated to Saint Mathurin. His wish was to be buried in the chapel and this happened in 1234. The construction work was finished by Pinchon's successor Philippe before his departure to the Holy Land in 1248. It was Bishop Philippe who moved to have Pinchon canonised on 12 April 1247.