Anne — as Christine said, it's a pen tray. Thompson gives Downing's address as Crown Works, Commercial Street, Birmingham. From memory, Commercial Wharf opened at the beginning of the century, so, by the middle of the century, there was a mix of heavy and light industry well established in the Commercial Street area. So Crown Works could have been a glass works, but, if so, it was one of the last in central Birmingham. I think it more likely that your pen tray was made in the Tyneside, Wearside, or Manchester glassworks.
Anyway, it's not too difficult to check in the Birmingham directories of the time. If you do, remember to treat directory entries with some scepticism — what you are looking for are new and changed entries, which can be regarded as reasonably reliable. As today, it was much less expensive for a directory publisher to buy all his competitors' directories and place a few advertisements in local newspapers requesting information, than to employ people to do the legwork around the streets, knocking on doors. You can sometimes find some wonderfully out-of-date entries!
One classic example is Hobson's Fox-hunting Atlas, which dominated this specialist field for over half a century. The first edition was an almost word for word transcription of an earlier directory onto C & J Walker's county maps, and quite legal, as the directory publisher had not thought it necessary to copyright his publication. It took Hobson about a decade to get his information reasonably up-to-date, and his meets in the correct place on the maps — the whole exercise apparently without the necessity to have ever set foot outside his premises!
Bernard C.