The major portions of Codex Sinaiticus that now reside in the British Library were bound into a volume by Douglas Cockerell after the leaves were closely studied by H.J.M. Milne and T.C. Skeat in their classic book, Scribes and Correctors of the Codex Sinaiticus (1938). So, if you visit the codex on display now, you will be looking at this handsome modern binding:

An opening of Codex Sinaiticus in its present binding; image source: codexsinaiticus.org

The decision to bind the leaves was not, however, without controversy. In a review of Milne and Skeat’s study in the journal Classical Philology, Kirsopp Lake lamented the new binding:

“The two editors, Dr. Milne and Dr. Skeat, are among the most competent in the world, but they are human. Questions will surely arise which, as they admit, can be investigated only when the leaves are loose. Why, after enjoying this opportunity themselves, have they acquiesced in the policy of rebinding the Codex and so prevented all others from seeing it under the same advantageous conditions? To me, at least, it seems certain that a codex such as the Sinaiticus ought not to be bound but kept in a box. This was the policy of the librarian at Leningrad, and the result was that I was able to photograph it under favorable conditions.”

The following issue of Classical Philology contained a response from Harold Idris Bell, who was at that time the Keeper of Manuscripts at the British Museum, and who had made the decision to bind the leaves:

“It is undeniably true that for certain purposes it is more convenient to handle unbound leaves than a bound volume. But Prof. Kirsopp Lake seem to forget that this is but one side of the position; he ignores another, and in my view even more important, responsibility of a librarian. A librarian’s first duty is surely that of conservation: he is responsible for seeing that the treasures committed to his care are preserved safely for the use not merely of contemporary scholars but of an indefinite number of future generations. Only subject to that over-riding responsibility can he make a volume accessible to any individual student or for any particular purpose. Now from this point of view I do not think that there can be any doubt as to which is the preferable policy. The leaves of the Codex Sinaiticus are extremely thin and often very brittle. At every handling there was a risk that portions of the edges would break away, and the vellum was constantly tending to “cockle” and the corners to turn inwards. Moreover it is very much more difficult to guarantee the safety of single leaves than of a bound volume. A collection of unbound leaves must be carefully counted (which, given the fallibility of man, means in effect counting at least twice) every time it is used, and both before and after issue to a reader. And the risk of the theft or loss of single leaves, even while they are reposing in their box, is considerably greater than with a bound volume. I may remind Prof. Kirsopp Lake that when he saw the Codex in Leningrad he was still able to photograph some scraps from Genesis and Numbers. These scraps never reached the British Museum. It is possible that they are still at Leningrad, but I have no information on this point, and we must, I fear, provisionally allow for their disappearance at some date between the photograph- ing and the sale to the British Museum. There is another consideration on which I would lay no great stress, for it is of a less ponderable kind than the risk of physical loss; but it is worth mentioning and is not without weight for any librarian or bibliophil. The Codex Sinaiticus is not just an article, a mere tool of textual criticism; it is a book, of venerable age and hallowed by its history and associations. It was bound in antiquity and later rebound at least once, and it was by a mere accident of fortune that it came into Tischendorf’s hands as a collection of loose leaves. To bind it, even in its imperfect state, with all the skill of the best modern craftsmanship (and Mr. Douglas Cockerell’s competence and taste are everywhere acknowledged), will seem to many an act of piety.”

From comments like Lake’s and Bell’s, I had been under the impression that the British Museum received a box of completely disconnected leaves with only fragments of earlier bindings surviving. But some fascinating newsreel footage from British Movietone (courtesy of the AP) shows that when the British Museum received the manuscript, the individual quires were still intact. If you listen closely, you can hear the leaves crinkle as the happy new owners mash the delicate leaves: