The vault of this transept is decorated with armored hallmarks, from North to South: from Penfeuntenio, Ménez, Virgin and Dourdu. The entrances were installed during the roof restoration in the 1960s. The panelling as those of the north transepts date from the great restoration of the years 1980-1990.
A huge semicircular bay illuminates the beautiful baroque altar of the Virgin placed in the center of the east wall, it hides the original altar (in stone). It is framed in height, in each corner,
on the left by Saint Christophe
and on the right Saint Jean Discalcéat (Sant Yan divoutou or Saint Jean le déchaux) the Santig Du (little black saint) dear to the Quimpérois (inhabitants of Quimper).
The altar was built in 1694, restored in 1861 and 1961. Its antependium (altar front) shows that the people and their king (the ermines around the sun of Louis XIV), must try to become saints such as those represented , on each side of the altar at the same level, by the gilded medallions of Saint Yves, the Breton, a lawyer but not a thief and of Saint Thérèse of Avila, reformer of the Carmel, set back. Saint Mary Magdalene and Saint Peter with his key and the rooster which recalls his triple denial.
Above the superimposed statues of Our Lady of Grace (the happy virgin) and the Pieta (The Virgin of Sorrows). The latter is framed by the medallions of the Virgin and of Christ in Majesty (in glory).
Above again, in his cloud, God the Father both young and old (for he is: He who Is) under his dove of the Holy Spirit.
On the choir side, above the large arcade, a large wooden painting from 1703 represents the reunion of Jesus and his Mother after the episode of the conversation with the doctors in the temple..
Below to the east are the remains of wall paintings.
In the southwest corner, two doors, one giving onto the cemetery, the other, older, onto the sacristy.
To the West, facing the altar, against the wall of the sacristy, coasters show: photocopies of documents, death certificate of Marguerite Moal, the Primelinois contract committing to buy the chapel in 1793 for the return to worship, old aspects of the church and of forgiveness, the chapels of the parish and the pendentives of the vault of the nave.