A Scribal and Illuminated Rebus?

Among the digitized manuscripts at Villanova University, PA, is a very small (approx.100×70mm) 14th-century English copy of some of Augustine's works, with a single illuminated page at the beginning:

[This and other images: Digital Library@Villanova University; Source]

The thing that strikes me as most unusual about this first page is the lower border, with foliage sprouting from what looks like a hole in the side of a wooden barrel:

I did not give this any more thought as I scrolled through the hundreds of page-images to see if anything else caught my eye, and only when getting to the very end of the text did I realise that the odd border-motif might be significant:

because at the very end, after the final "Amen", are the letters "bur" and a sketch of what appears to be a barrel, or tun:

I take this to be a scribal rebus: bur + tun = Burton. Perhaps I am reading too much into this tiny sketch, and over-interpreting the motif in the illuminated margin, but it seems at least possible that the book was written by a person named Burton, and they wanted it to be discreetly "signed" at both beginning and end.

As for the book's later provenance, a printed and typescript label tells us how it got to Villanova:

de Ricci (Census, II, p.2132, no.1) tells us prior to this it was in the W.J. Leighton sale in London, 14 November 1918, lot 75; bought by Tregaskis, and in their Catalogue no.915 (1925), no.260; from whom it was bought by John Frederick Lewis. The manuscript also contains a clipping from the Tregaskis catalogue:

Below this a price-code with a single-digit number of pounds sterling, "R/-/-"; in the next post I'll consider whose this mught be:

It seems extraordinary that de Ricci does not mention one other obvious piece of the provenance. At the front of the volume is a large red gilt leather bookplate (which was the subject of a blog-post at the Folger Library a couple of years ago) of the well-known bibliophile Edward Hailstone (1818-90):

IF (a big "if") our scribe's surname was Burton because his family came from Burton-on-Trent, in the north Midlands, it may be significant that Hailstone lived first at Bradford, and then Wakefield, about 70 miles north of Burton: perhaps the manuscript was in that part of England from the Middle Ages until the 19th century?

The published auction and dealer catalogue descriptions from 1891 to 1925 present some problems of identification, and so I'll keep them for a separate post.