It is a little difficult to date these windows. They cannot of course be earlier than 1185, but I do not think that any of them are much later than 1220, though from the fact that one of the medallions, and one only, contains a representation of the famous shrine--everywhere else it is the martyr's tomb in the crypt that is shown--the particular window containing it cannot have been executed before the latter date, as the shrine would not have been in existence. It may, however, have been done in that year. This window and the one next it seem to me to be by an inferior hand, and contain certain features not found in the others, but common in later glass of the thirteenth century.
Whether this represents a gap in the execution of the windows it is, however, impossible to say without the evidence of the windows which have been destroyed. Seeing that from 1208 to 1213 the country was under an interdict, the existence of such a gap would not be surprising.
None of the windows are entirely filled with their original glass, but four of them are nearly so. The gaps have been filled up with most ingenious imitations of the old glass, executed from 1853 onwards by Mr. Caldwell, under the direction of Mr. G. Austin, and so cleverly are they done that they are very difficult to detect by the eye alone. I do not think that "restoration" of old glass, by which is usually meant filling up or replacing it by imitation of the old work, is ever justifiable, but I am obliged to admit that, if it ever could be so, it has been justified here at Canterbury. I think there is not much doubt that in these four windows, at least, one can see the old glass better for the gaps being filled up with colour than if they had been left white. The principle, however, is a bad one, and I have seen little "restoration" elsewhere that did not disfigure the window.
Fortunately a most indefatigable lover of stained glass, the Rev. J. G. Joyce, has left a series of coloured drawings of the glass as it was in 1841 before restoration. These and his manuscript notes are now in South Kensington Museum, together with some coloured tracings by a Mr. Hudson, and enable us to trace what has been done. From these we learn that in his time the place of the Crucifixion in the east window was occupied by a figure of the Virgin from a Jesse window, proving that there was once a Jesse window at Canterbury as well as elsewhere. Judging from the tracing, the scroll work of the "tree" follows closely the lines of those at Chartres and St. Denis, but is a little more elaborate and very beautiful. It seems to me more in keeping with the earlier than the later work at Canterbury. Unfortunately no one seems to know what has become of it; but Winston who saw it, quotes it in a lecture as "some of the oldest glass in the country." If the Cathedral authorities have got it stowed away anywhere I hope they will some day place it in one of the empty windows where it can be seen.