The third floor, also entered by a Tudor doorway from the staircase, is of the same dimensions with the floor below. In the east wall is a fireplace, also Tudor, and in the west wall, at the north end, a square-headed door, opening into the third floor of the appended chamber. This chamber has a Decorated window in its north wall, and had a timber floor and ceiling, and is crossed by a round-headed arch which supports the south wall of the north-west turret. A weather-moulding in the south wall shows that this appendage had at first a lean-to roof.
The south wall of the main chamber has also a weather-moulding, showing that this wall was once a gable, and that the keep had originally a high-pitched roof with a central ridge. A Tudor window has been inserted into the wall, and cuts through the moulding. The north wall is pierced by two round-headed recesses, in which are trefoil-headed windows of one light, and apparently of Decorated date. There is no weather-moulding at this end, one of the many indications that this wall has been rebuilt. This floor, like that below it, is 11 feet 10 inches high, and from it nineteen steps ascend to the battlements, opening by a Tudor door at the stair-head. The stair ends in a rectangular turret, 15 feet by 9 feet. The north-west turret, 8 feet by 10 feet, has no opening from the ramparts. The two southern turrets are larger, and both have exterior staircases of twelve stairs leading to their flat roofs. The south-west turret is 15 feet by 14 feet, and the south-eastern, not now accessible, is about 15 feet square. The north and south walls are here 5 feet thick, two being occupied by the embattled parapet. The east wall is 9 feet thick, and contained a double chimney-flue. The west wall is double, the inner 4 feet thick, being the wall of the keep, and the outer 3 feet to the wall of the appendage. The space between, 5 feet 8 inches broad, was covered by a flat roof, so that the rampart here was 12 feet 8 inches broad within the parapet. There were two embrasures on each face of the keep, and the roof last laid upon it was flat.
The keep seems originally to have been built by Roger de Lacy, 1086 to 1096, as a plain
-shaped tower, upon and a part of the curtain wall. It had a basement floor at the ground level, and one upper floor of considerable height, with an open, high-pitched roof, of which the north and south walls, nearly if not quite of their present height, formed the gables, just as in the Norman gatehouse of Sherborne Castle. Probably the side walls were nearly as high as the gables, so as to conceal the roof. The basement was entered at the ground level by a door in the north wall. It had at least two arches of an arcade in each of its side walls, and was probably divided by a cross wall into two chambers, the inner being entered by the passage in the east wall. The entrance to the upper floor was also on the ground level, but in the east wall, and therefore in the middle ward. It was by a small door and short passage, from which, on the south or left, a staircase threaded the east wall, and landed in a vaulted lobby at the level of the first floor. This lobby and one opposite to it led out upon the curtain. How the keep battlements were reached is uncertain, possibly by the present well-staircase, which, in that case, then commenced at the first-floor level.
The first alteration made in the Norman period was probably a century later than the original building. This consisted in the addition of a building on the west front, filling up the hollow angle of the
. It contained a basement, which seems to have been a cesspit, and is now entered by a breach, and is vaulted. The roof was a lean-to. To enter the first floor of this building a door was opened in the wall of the keep. Also on the opposite or east side a mass of masonry was built into the hollow angle of the
. This, however, stopped at the first-floor level, and was probably intended to give a second passage between the first floor and the gatehouse. In the block was a vaulted prison cell for the porter, and a passage which led into and covered the entrance of the keep.