Ker included in his book a survey of Oxford binding. Much of what he had to say has been superseded by David Pearson's 2000 volume on the subject. The final section of Ker's survey, however, remains relevant as it was cited in Ker's Introduction.
Methods of Securing Endleaves
Before c. 1540. The parchment pastedown and the accompanying paper flyleaf are cut a little wider than the book in which they are to be used. The extra width is folded an taken round the end sections, or projects as a narrow turned-up strip opposite the title-page. [p. 227] A string runs down the fold and is fastened to the sewing at the bands. Sometimes the place of the paper flyleaf is taken by a narrow fold of paper lying in the fold of the parchment pastedown.
After c. 1540. The parchment pastedown and paper flyleaf are cut, at first, a little wider and, later, considerably wider than the book in which they are to be used. The extra width is folded back so as to produce a double thickness of material along the part of the cover next to the back. The folded edge of the paper flyleaf is pasted to the cover beneath the pastedown, and both pastedown and flyleaf are further secured in position by a string running down the fold and fastened to the sewing at the bands.
So far as I have noticed all pastedowns up to no. 199 in my list are folded according to the first method and all pastedowns from no. 301 according to the second, with a few exceptions. The binder who used rolls V and VI and the rolls associated with them (nos. 200-300) began by using the first method and changed to the second after a few years. A majority of bindings with these rolls have, unfortunately, been repaired so that it is no longer possible to be sure which method the binder used, but I have noted seven examples of the first method in the bindings of books printed in and before 1538, and twenty-one examples of the second method, ten being in bindings of books printed between 1539 and 1544. The dates of printing show that the binder did not use the two methods indifferently, but generally the first for his earlier and the second for his later bindings. We would expect to find some variation at the time the change took place and, in fact, no. 217 shows both methods being used in one binding, the pastedown at the beginning being turned up opposite the title-page and the pastedown at the end folded back.
In making the change the binder may have been imitating the practice of the Oxford binder who used roll VII and presumably began his binding career here in or soon after 1537, the date inscribed on the roll. Or he may have invented the new method for himself. Two of his bindings at Ripon (no. 293a) are interesting in this respect, since they suggest that he was making experiments. In each of them the pastedowns and flyleaves are turned up round the end-sections in the old way and, as additional strengthening, six strips of parchment are laid round the back between the bands and half-bands and pasted to each cover underneath the pastedown. I have not noticed any other example of this method.
The new method introduced in Oxford c. 1540 did not, it seems, make its way to Cambridge for a decade or more. My impression, from a limited survey of Cambridge bindings, is that it was not used there in the forties, but that some Cambridge binders used it and others did not in the fifties and sixties. Any pastedown which shows signs of having been folded back is more likely to come from an Oxford binding than from a Cambridge binding. There are many such pastedowns in the guard-books, &c., of Oxford college libraries, especially at Merton, which I have not listed because they cannot now be shown to come from the binding of any one particular book.
 Exceptions I have noticed are the pastedowns in bindings with centrepiece xiii and some of those in bindings with roll XXII (nos. 1221, 1223-4) and centrepiece xxix (nos. 1961, 1963, but not 1962).
 Nos. 200, 214, 215, 278, 281, 289, 293a.
 Nos. 202, 204, 217, 246( ?), 249, 252-3, 262, 266, 269, 270, 272, 274a, 279, 283, 288, 293, 293b, 293c, 296a, 296b.