sometimes the clear plain undecorated examples are seen commonly at big fairs - those with cranberry bowls far less so - but in the 10 - 12 years I've been looking for custards, this is the first example I've seen of something other than clear or cranberry.
The handle indicates a pre 1870 date, and the ground/polished pontil, whilst a tad rushed, is of reasonable quality. Sold to me as either shot or toddy glasses from the C20, and I didn't rush to correct the seller.

Height is about 3.1/16" (78mm).
So, they're rare - but 'as hens' teeth', or does everyone else have shed loads of these things, and I'm deluding myself as usual

All thoughts welcome - especially as to country of origin - and thanks for looking.