Hi â€” Sowerby pattern No. 2597, launched c. 1937 give or take a year or two. Launched in two sizes, 5" and 10". Later an intermediate size was added 7Â½"?, 8"?. I would be grateful for an exact measurement. Some post-war examples have sandblasted interiors.
I believe that some were sold pre-war by imaginative retailers as garniture sets, with a 10" 2597 flanked by two 5" 2597s, as they crop up like this more often than you would expect.
Colours include flint, amber, greens, blues, Rosalin (Sowerby's highly variable pink), amethyst, black, and, the most desirable, uranium yellow.
Gareth â€” BGbtW #169 was probably the reference you were looking for.