 There are 13 stained glass windows in the upper choir area, 5 on the north-facing side, 5 on the south-facing side and 3 in the ambulatory and these were installed in the time of Monseigneur Bertrand de Rosmadec and when, from 1417 to 1419, the choir vaulting was installed.They are the work of the Quimper glass painter Jean Soyer (or Souhier) and were possible because of the largesse of the Breton nobility and church.These benefactors are shown in the 13 windows on their knees and in the company of their own particular patron saint.