In another place he goes further still:—
"Gloucester, a royal castle, stood on the Severn bank, at one angle of the Roman city. It had a mound and a shell-keep, now utterly levelled, and the site partially built over. It was the muster-place and starting-point for expeditions against South Wales, and the not infrequent residence of the Norman sovereigns."[953]
It may seem rash, in the teeth of these assertions, to maintain that this mound and its shell-keep are alike imaginary, but the word "turris" proves the fact. For, as Mr. Clark himself observes with perfect truth,
"in the convention between Stephen and Henry of Anjou (1153) the distinction is drawn between 'Turris Londinensis et Mota de Windesorâ,' London having a square keep or tower, and Windsor a shell-keep upon a mound."[954]
So the keep of Gloucester, being a "turris" and not a "mota," was clearly "a square tower" and not "a shell-keep upon a mound." The fact is that Mr. Clark's assertions would seem to be a guess based on the hypothesis, itself (as could be shown) untenable, that "Brichtric had a castle at Gloucester." Assuming from this the existence of a mound, he must further have assumed that the Normans had crowned it, as elsewhere, with a shell-keep. But the true character of this great fortress is now determined.
Two examples of the double style shall now be adduced from castles outside England. In Normandy we have an entry, in 1180, referring to expenditure "in operationibus domorum turris et castri," etc., at Caen;[955] in Ireland the grant of Dublin Castle to Hugh de Laci (1172) is thus related in the so-called poem of Matthew Regan (ll. 2713-2716):—
"Li riche rei ad dune baillé
Dyvelin en garde la cité
E la chastel e le dongun
A Huge de Laci le barun."