I suggested that a good clue would be whether or not a bible listed in the catalogue of Henry's books published in 1880, as being bound in BR[own] M[orocco], could be identified with the Haddaway Bible, which is known to have been lot 645 in the sale of the Huth Library at Sotheby's, 15 November 1911, and following days. If the Haddaway Bible, when sold in 1911, did NOT have a brown morocco binding, then it is almost certainly not the one described in the 1880 catalogue, and my hypothesis would be proved incorrect.
On reading that blog, Bill Stoneman very kindly consulted a copy of the 1911 catalogue and sent me a scan of the relevant pages:
It is also notable that the early 13th-century manuscript is incorrectly dated "XIVth Century", just as the manuscript had been in the 1880 catalogue. It therefore seems that we now have proof that the Haddaway Bible did indeed belong to Henry Huth.
But Bill then went further and made a remarkable discovery. Next to the Huth auction catalogue on the shelves at the Houghton Library is a finely bound copy of the 1880 catalogue, with (i) the Huth leather book-label on the upper pastedown,
These enhancements demonstrate that this was Alfred Huth's own copy of the catalogue of his father's library.
The marginal annotations next to each catalogue entry consist of a price, an initial letter (such as "E", "L", "Q", and "S"), and a two-digit number.
The price is doubtless the purchase price (or possible a probate valuation?), the initial letters must indicate the source (since "Q" is unlikely to stand for anything other than Quaritch), and the final two digits are presumably the year: on the pages shown above they range from 56 to 76. If "Q" is Quaritch, "E" is probably F.S. Ellis, "S" is probably Sotheby's, and "L" is doubtless Joseph Lilly: according to the ODNB entry on Henry Huth, "Joseph Lilly ... exercised a good deal of influence on his purchases over the years and was generally his agent".
The next step in tracing the provenance of the Haddaway Bible will therefore be to trawl auction and Lilly catalogues for 1856. For the latter, David Pearson's Provenance Research in Book History: A Handbook, tells us "The best collection will be found in the Bodleian Library, which hold about 180 Lilly catalogues, 1827-70 ... many of these were previously Sir Thomas Phillipps's copies".