Near the west end of the north wall is a second doorway—now walled up—and in the north-west angle a doorway leading into a stair turret. The vaulting is quadripartite in the centre and western bays, but sexpartite in the eastern one. The ribs spring from carved and moulded corbels, themselves springing from the string round the building. The vaulting ribs are about 9 inches thick, well moulded with a centre and two side rolls and deep hollows between, the transom ribs having the hollows filled with acutely pointed dog-tooth moulding, the diagonal ribs being without it. The springing of these ribs is about 10 inches above the corbels. There is no ridge rib, but there are well-carved bosses at the intersection of the diagonal ribs, the centre and western ones being all foliage, the eastern one foliage, with the _Agnus Dei_ in the centre. Externally the building is divided into bays by rather flat buttresses of about 1 foot 6 inches projection, running up into a corbel table on the two side walls. The corbels are simply chamfered, and carry an equally simple cornice. At the north-west angle the two buttresses are of rather greater projection and of considerable width, giving space inside them for the staircase mentioned before. The west doorway is an excellent example of good Lincolnshire thirteenth-century work, the arches well moulded and enriched with dog-tooth, the jambs having one attached and two detached shafts with well-carved capitals. The carving of these and all the other capitals in the chapel is of the stiff “celery” stalk foliage so common in Lincolnshire work, and all, equally with the mouldings, refined and evidently the work of high-class masons and carvers. Internally there are no ancient features beyond those already mentioned, except a very simple triangular-headed piscina in the eastern bay of the south wall. The projecting part of its basin has been broken off, but two grooves for a wooden shelf remain. The chapel, being a donative without restriction, was used as a Presbyterian chapel from 1720 to 1812, and was then filled up with pews, and a pulpit of Jacobean character, apparently previously in the chapel, was erected in front of the east window. Most fortunately, however, in thus fitting up the chapel, the joiner incorporated in the pews two pieces of an Early English screen, of an exceedingly interesting description, and which no doubt originally cut off the eastern bay from the body of the chapel. These two pieces are each about 6 feet long, and consist of an open arcade, the upper part of the screen, each having six trefoil-headed openings, the heads being cut out of boards only ⅞ inch thick and rudely pinned on to uprights 2⅞ inches square worked into octagonal shafts 1¾ inch in diameter, with moulded caps and bases. The whole work is somewhat rude in execution, but is an extremely valuable specimen of early woodwork.