The college reserved the quire for its own services, while the parishioners of the old peculiar of the priory used the nave and transepts. The ante-chapel of Merton college chapel at Oxford was used till quite lately as the parish church of St John Baptist. § 22. No better instance of the complicating influence of chantry chapels on the plan of a parish church could be given than the church of St John Baptist at Cirencester. The oldest part of the present building is the chancel with its south chapel, which contain twelfth and early thirteenth century work, but are in the main the fruit of a later thirteenth century reconstruction. The north chapel, known as St Katharine's chapel, is a rather narrow aisle, communicating with the chancel by fourteenth century arches. North of this, again, there may have been a lady chapel on part of the site of the present one. Towards the middle of the fifteenth century, the aisles of the nave were much widened, the width taken for the new north aisle being about twice the width of St Katharine's chapel, and the new south aisle being rather wider than the south chapel of the chancel. The Trinity chapel was formed by adding to the nave an extra north aisle, about half as long as the adjacent aisle, from which it is divided by a stone screen. There had been an earlier altar of the Trinity in the church; for the licence granted to Robert Playn and others in 1382 to found a chantry of two chaplains in Cirencester church placed one at the altar of the Trinity, and the other at the altar of St Mary. In 1392 another chantry was founded in the lady chapel. But, in its present state, the lady chapel seems to belong to the later part of the fifteenth century, when it was probably much broadened, so as to overlap the east wall of the Trinity chapel. Both it and St Katharine's chapel open into the north aisle through four-centred arches: they open into one another by two arches pierced in the intermediate wall. Between these arches has been left a thin piece of wall, in which rectangular slits, commanding the altar of the lady chapel, have been cut. The plan thus includes two chapels north of the chancel, and another north of the nave, as well as the south chapel of the chancel. The rebuilding of the nave, with its splendid south porch, its smaller north porch, and its western tower, was not completed until early in the sixteenth century. The Jesus chapel was enclosed within screens at the south-east corner of the south aisle; and the roof of St Katharine's chapel was heightened, and provided with fan vaulting. [Illustration: Fig. 2. Plan of Cirencester Church.]