Hi Peter, welcome to the board. It sounds like an interesting research project you are doing. I presume you have seen the entry on Charterhouse Buildings with an engraving of the aftermath of the fire here?
http://www.british-history.ac.uk/survey-london/vol46/pp385-406#h3-0005You are correct that Chapman Son & Co appear to have made Dressing Cases. Oliver Chapman (1816-1880) was a cabinet maker by trade (1841 census), who is shown on all subsequent census up to and including 1871 as a dressing case manufacturer.
In 1861 Oliver's older sister was listed as a jewel case liner, his son William O Chapman was a jeweller, son Oliver a surgical instruments maker. Middleton was shown as a traveller in 1861 and by 1871 he was a dressing case manufacturer, by 1881 as a merchant of fancy goods he was employing 18 men, 7 women and 4 boys. There is no trace of him or his wife in the 1891 census, but in 1901 he was shown as a dressing case manufacturer and in 1911 a merchant dressing cases.
Another of Oliver's sons Frederick J Chapman is shown on the 1871 with him as a dressing case manufacturer, and a daughter Hannah E Chapman as a dressing case liner. Middleton living elsewhere in 1871 has living with him and his wife, his 16 year old brother in law, William J Noyes (1855-1924), a silversmith apprentice. Middleton's daughter married Thomas A Milo, who was manager to a manufacturer in 1901 and later a marble seller in 1911.
So, to my eyes it looks like many of the family may have worked within the business. The glass was either commissioned from a glassmaker or maybe they used standard designs, and added silver trim, lids etc.... which was not uncommon.
Having worked through all of the above, I then found the following information, which you may already have, but if not, it supplements the census info...
Grace's Guide: https://www.gracesguide.co.uk/M._Chapman,_Son_and_CoM. Chapman, Son and Co
of 2 Charterhouse Buildings, Goswell Road, London, EC1. (1922)
("Chasoco") Ditto Address. Telephone: Clerkenwell 5868, Cables: "Tantalus-Barb, London". (1929)
1798 Company established.
1922 Listed Exhibitor - British Industries Fair. Manufacturers of Automatic Tables and Cabinets for Writing, Smoking, Liqueurs, Work, etc.; Dressing Cases, Leather Goods, Mounted Glass. (Stand No. E.25) [1] Ref. 1922 British Industries Fair p16
1929 British Industries Fair Advert for 'High-Class Fancy Cabinet Goods', and various folding tables. Surprise Spriit, Cocktail, Smoking, Writing, Tea Tables, Self-closing action. Tantalus Spirit Stands, Smokers' Cabinets. Writing Cabinets. Work Tables. Cigar and Cigarette Boxes. Chapman's Patent Lock Bottles. (Jewellery Section - Stand No. J.76) [2] Ref. 1929 British Industries Fair Advert 65; and p38
Image showing one of the dressing cases....
https://www.gracesguide.co.uk/File:Im1929BIF-Chapman.jpgSilver Marks:M.C was registered as a silver mark by M Chapman, Son & Co Ltd (Middleton Chapman) 1903..1919 (registered Feb 1892 & 1901, 1909, 1910)
https://www.silvermakersmarks.co.uk/Makers/London-MA-MC.htmlCabinet Maker:"... in December 1900, Nat signed a five year indenture as an apprentice cabinet maker with M. Chapman, Son & Co., a ‘top of the range’, furniture manufacturer, who operated from premises at, 2 Charterhouse Buildings, Goswell Road, London, EC1."
https://www.78rpmcommunity.com/beta/78rpmcataloger/charles-nat-star-a-life-in-music/Finally, going back to Henry Herbert as a publisher of handbooks etc, publishers were often stationers as well, and we have examples of stationers having glass inkwells registered in their name, again they would have commissioned a glassworks to make them for them.