The well-marked plinth of this east end has been already noticed. Either corner of the choir contains a staircase, and is strengthened by a pair of massive buttresses and crowned by an octagonal turret with a conical stone cap and a finial. These buttresses have a projection of 8 feet, rise to the top of the aisles, and are surmounted by gables with finials, and at the north corner the gables and the coping of the aisle are crocketed. At the south corner the upper part of the turret has been used as a cell. It is lighted by a small slit and has a wooden floor with a trap in it, from which a ladder once descended to the head of the staircase; and at the west side, in the parapet of the aisle, there is a garderobe seat. It would be interesting to know whether this turret was a prison, or a place of penance, or whether it was occupied by a watchman or sentinel, or, as is not improbable, by one of those recluses who were so often attached to religious communities in the middle ages. The central compartment is flanked by two huge buttresses, which have a projection of 10 feet at the bottom and rise to the base of the gable, or rather a little above it, in two stages only, the lower stage reaching a little above the coping of the aisles, and both stages are crowned by gables with finials.[52] The three compartments of the front are on the same plane. Each aisle shows at the end a window of the same pattern with these in the sides, and that in the south aisle has foliage on the capitals of its shafts and is surmounted by a little window of trefoil form which lights a staircase within, for staircases ascend over these windows in the thickness of the wall and run up the angles of the clearstorey.