Ah. So you're in Westpondia! It could be a significant advantage as much of the best Walsh was exported there. Some of Eric Reynolds' best pieces came from the USA.
To explain:-
1. Leibe/Hayhurst is Miller's Glass of the '20s & '30s, A Collector's Guide, 1999.
2. Reynolds (Eric) is The Glass of John Walsh Walsh 1850-1951, 1999.
3. "mother of pearl" uncapitalised, with or without hyphens, has nothing to do at all with the US collector expression "MOP" or "Mother of Pearl" which was one manufacturer's trade name for air trap that was genericised by one of the early US authors, possibly Heacock, apparently under pressure from his publisher as a device to force collectors to buy his books, unnecessarily, as it turned out, as Heacock's books were so good. It's use in the Walsh context indicates a range that looks like natural mother of pearl or nacre, dating from the late C19, and found in flint, canary (yellow uranium) opalescent, green, probably amber, and possibly other plain or opalescent colours. It's distinguishing feature is that the tiny initial gather was of white opal, probably a lampshade glass. You can see this best on stemmed examples. Sometimes this very thin inner layer can be seen as a fine crackle effect on the inside curve of a flared rim. I believe the expression mother of pearl in this context was first used by Leibe/Hayhurst. It is likely that it would be replaced by Walsh's own name for the range if we could discover it.
4. Correction. The canary opalescent Walsh pieces in Gulliver and Reynolds are probably not mother of pearl as I said above. Canary opalescent mother of pearl is quite rare - I sold my only certain example for some years at Cambridge last month. It can be quite difficult to distinguish between the two, although the iridescence on mother of pearl helps, that is, if you are prepared to accept that, at the time, only mother of pearl was iridised. My experience is that general rules like that always throw up exceptions.
Hope that helps,
Bernard C.
