A group photo that includes: (top row) several examples of unmarked insulators commonly referred to as "Pennycuicks", (middle row) several examples of N.E.G.M.Co. insulators that show "Pennycuick" features. (bottom row) the Knowles insulators being discussed that show some "Pennycuick" features.

I chose some NEGM insulators that exhibit Pennycuick features to compare to the Knowles ones. My NEGM examples lean heavily toward the green end of the spectrum, but that is why they ended up in my collection (I think I've traded or sold most of my aqua examples!) I have seen a lot of them at shows though, and some are very close matches to the Knowles examples here in color. And several of the green NEGMs are very close to the green M&E Co/Knowles CD 252. Incidentally, the CD 267 is NEGM [010], a pretty rare bird in my experience. It has no patent date, and shows "Pennycuick characteristics". So do many (but not all) of the CD 251 NEGMs without patent dates. One possibility is that NEGM made the Knowles insulators shown here. I think I am starting to lean in this direction.

The unmarked "Pennycuicks" here were picked because they had color and glass character similar to the Knowles examples. It is quite true that these unmarked Pennycuicks are also found in extremely bubbly junky glass, and also in some wild colors I've never seen in the Knowles examples. This variation could hint at different manufacturers, or could indicate different production periods of one manufacturer. Hard to say at this point.

Does any of this mean that the NEGM insulators were made by the same company as the unmarked Pennycuicks? No... It could also be that NEGM acquired some of the equipment once used at the company that made the unmarked "Pennycuicks", and used it in their production. Or, maybe they just used similar techniques. If they used the same (or very similar) source for their sand, it could also explain any similarities in glass color.

As I see it, the colors on these Knowles lean a little more toward "fuggly aqua" than the typical Elmer production, but this whole area needs a lot more observation & discussion before any consensus can be approached...