The church, which is situated about eighty yards east of the castle, is a large and very spacious cruciform structure of stone (probably Ancaster, which has weathered well, and looks in many places as though it had been worked a year or two ago), consisting of nave, with aisles, choir, north and south transepts, a north porch, doorways in the west and north aisle of nave, south transept, and door in choir, and western tower. There have been cloisters on the south side of the choir to which this door gives entrance, and two porches corresponding to that existing on the north side, and the other at the south end of the south transept. It is 180 feet long, the transepts together are 100 feet in length, the nave 60 feet wide, the chancel 26 feet, and the transepts 20 feet. Over the entrance to the north porch is a niche for a statue, below a handsome cross, and above a shield, with the coat of arms of William of Wainfleet, Bishop of Winchester, to whom some part of the architectural design of the castle has been attributed (he is supposed to have finished this church after the founder’s death), _i.e._ fusilly ermine and sable, and on a chief sable, three lilies slipped. Over the south porch was a similar shield according to Holles; in the windows above both porches was the inscription: “Orate pro anima Radulphi nuper domini de Cromwell et Tateshall, Thesaurarii Anglie et fundatoris hujus Collegii.” On the west side of the door of the north porch is a holy water stoup. Over the east window of the choir is another niche, probably for the Holy Trinity. The tower has a fine square-headed western doorway beneath a band of panels containing blank shields, a five-light window above, then a small square-headed light, and three-light belfry windows. The parapet is now plain, with crocketed angle pinnacles, which end, below the parapet, in double angular buttresses, a feature not uncommon in Perpendicular towers, but not much to be admired—especially here, as it makes the tower look rather low and squat. There is a staircase in the south-west angle of the tower, leading also on to the aisle roof. At the junction of the choir and south transept is a circular turret, in which is a staircase from the pulpitum or choir screen, up to the transept and nave roofs: it has been higher, and probably was used, as in so many other Lincolnshire churches, as a Sanctus bell-turret. The first great impression gained on entering the chancel is its exceeding lightsomeness, the window surface is very extensive, compared with the wall space, and unfortunately, except in the east window, all the coloured glass is gone. This came about in 1759, from the then Lord Fortescue giving the then Earl of Exeter the glass from the windows to put in St. Martin’s Church, Stamford,[96] on condition that the Tattershall windows should be glazed with plain glass. This condition was not observed for many years, and the interior of the church, particularly of the choir, suffered terribly