Over the window may be seen the mark of one of the earlier roofs. The choir is thought to have received a groined vault of oak after the rebuilding of the east end, but this vault was probably renewed more than once, especially after the accident to the tower about 1450, and the fall of the spire in 1660. Sir Gilbert Scott found a vault of lath and plaster (probably the work of Blore) for which he substituted the present roof, a groined wooden vault, admirable in its lofty pitch and judicious colouring. Its chief feature, however, is the splendid bosses along the ridge, which are survivals from either the Decorated or a subsequent Perpendicular vault. In some of these bosses the figures are five feet long. From west to east the subjects are as follows: (1) A head; (2) an angel, with foliage; (3) a head; (4) a man conducting a woman to a church door; (5) a bishop in benediction; (6) a king enthroned; (7) a bishop enthroned; (8) a king and a bishop enthroned together; (9) the Crucifixion (modern); (10) the Annunciation; (11) the expulsion from Paradise; (12)? the good Samaritan; (13) a head. There are also good foliage bosses against the walls between the pendentives. The westernmost pendentive on either side rests on a Perpendicular corbel carved with delicate foliage. The general arrangements of the presbytery have been much changed since the middle ages. The altar then stood against a screen one bay in advance of its present position, and the iron hooks upon the second complete column from the east end on either side held, it is supposed, the Lenten Veil. Before the last restoration the altar stood, as now, against the east wall (on a single step, however), but the Sanctuary still extended two bays westward and was three steps above the rest of the choir, which was all on one level. Since then the floor has been raised one step at the east end of the stalls, and the steps to the Sanctuary have been diminished by one, while there are now two steps to the altar, and the Sanctuary and the raised portion of the choir have received an inlaid marble pavement. The reredos, an arcading of slender arches each enclosing a trefoiled arch impaling a trefoil, is a restoration of the original Decorated work. The latter had been covered by a painted screen of wood--possibly of late mediaeval workmanship--and this again by a huge oil-painting of the time of Charles II. Both were removed to make way for a high reredos by Blore, which in its turn was taken down by Sir Gilbert Scott.[96] On the pavement south of the altar is a piscina, which (if this be its original position) must have belonged to a chapel or chantry behind the high altar--possibly the chantry of the Holy Trinity _subtus altare_.[97] From its position it would seem that in those days the floor here was considerably lower than it is now. [Illustration: THE SEDILIA.]