The plan of the castle gatehouse at Warkworth was that of the great majority of medieval gatehouses, whether in castles or in the walls of fortified towns. The ground-floor of the main block of building, which generally had two upper floors, contained the hall of entry, and was flanked by two cylindrical or octagonal towers, the lowest stories of which were guard-rooms, and were pierced with loops commanding the approach and the passage. Usually the gateway was placed at the back of an arched recess, which formed a porch. The position of the gate and portcullis at Warkworth was rather exceptional. Ordinarily the portcullis descended in front of the gate, which opened inwards, and was secured, when closed, by one or more draw-bars. This, however, was impossible, where the gate, as at Warkworth, opened outwards, so that the usual arrangement had to be reversed. But, while the actual plan of the gatehouse kept its general characteristics with little change, the defences of the entrance were multiplied. Thus the Byward tower, the outer gatehouse of the Tower of London, had an outer portcullis in front of a wooden door opening inwards, behind which was a second portcullis, blocking the entrance to the inner and wider portion of the passage, which had a timber ceiling. In addition to this, between the outer portcullis and the gate, the vault was crossed by a rib, pierced with three holes, which allowed the defenders to harass an attacking party from above, and also could be used for strengthening the gate in time of siege by a timber framework, the upper ends of which were fixed in the holes. Such holes, which were not merely machicolations in the vault, are found elsewhere, as in the gatehouses of Pembroke and Warwick castles and the west gatehouse of the town of Southampton. In this last case, a single rectangular gate-tower projected from the inner face of the wall only, next the town. The gate of the passage through the ground floor was defended upon its outer face by these holes alone: there were two portcullises, but both were upon the inner side of the gate. It is possible that such holes were originally left to fix the centering of the vault when it was first built: they converge towards one another, and probably were not filled up afterwards, in view of their defensive use.[247]
One prominent feature, however, of the defences of a gateway, as time went on, was the provision of machicolations, in the shape of long rectangular slits, in the vault of the passage and in the arch in front of the portcullis. In some cases where they occur in connection with a portcullis, they may have been used for a heavy wooden frame, which could on occasion reinforce the iron herse of the portcullis. At Warkworth there is no original arrangement of this kind: the wall of the first floor above the gateway projects slightly upon a row of corbels, but this was done merely to give it additional strength. At a later date, however, the parapet at the top of the gatehouse was corbelled out, and the spaces between the corbels left open for machicolations. From the later part of the thirteenth century onwards, the usual arrangement, as at Chepstow or Tutbury, was to carry the parapet upon an arch in advance of the main face of the gatehouse, from one tower to the other, and to leave the space between the parapet and the main wall open, so that it commanded the field immediately in front of the portcullis. The effect of recessing the front of the gatehouse within a tall outer archway is magnificent, from the point of view of design. The design of gatehouses reaches its highest point in the great gatehouse of Denbigh, with its octagonal gate-hall, and in the King’s gateway at Carnarvon, where the enclosing arch, recessing the two lower stages of the gatehouse, bears the outer wall of the upper floor ([253]).
Pembroke Castle; Interior of gateway
In some instances, as at Pembroke ([224]) and Kidwelly ([225]), where the gatehouse passage was defended by inner and outer portcullises, there are as many as three chases or slots in the vault between the outer and inner entrances. At Pembroke, where the gatehouse has the unusual feature of two flanking towers ([213]), of semicircular projection, on the side next the ward, an arch was thrown out from one tower to the other, some distance in advance of the inner archway. It is difficult to see how this inner barbican, as it may be called, was intended to be of use to an already strongly protected gateway; but the space within it may have been covered by a wooden platform, accessible from the first floor of the gatehouse, from which the interior of the castle could be commanded, and an enemy who had forced an entrance could be seriously annoyed. The vault of the entrance passage was generally a pointed barrel-vault, strengthened by transverse ribs at intervals; but the broader space in the centre of the passage was often ceiled, as in the Byward tower, with timber. The entrance passages of the inner gatehouses of Harlech ([274]) and Beaumaris ([236]) were roofed with wooden ceilings, supported by transverse ribs of stone set with only a narrow interval between them.
Kidwelly Castle; Interior of gateway
The ground-floors of the flanking towers of the gatehouse were usually vaulted. The lodges from which the towers were entered, upon each side of the inner passage, had stone ceilings when the passage itself was vaulted through its whole length, or when they formed one room with the ground-floors of the towers. The ordinary plan, however, was to treat the flanking tower as an outer guard-room, approached from the inner lodge. If it was cylindrical in plan, the interior was arranged as a polygon, and vaulted with ribs springing from shafts in the angles.[248] This plan may be seen in the Byward tower and Middle tower of the Tower of London. In both towers the inner part of the passage was ceiled with timber, and the adjacent chambers formed lobbies to the vaulted ground-floors of the towers. In the Middle tower, however, the left-hand lobby was occupied by a vice leading to the first floor; and in the same position in the Byward tower is a square rectangular chamber with a ribbed vault.
Rockingham Castle; Gatehouse