Rare Chippy Ironstone Measuring Cup - with Number 15

A delightful white ironstone early to mid 20th Century tablespoon measuring cup, with a very rare number to the front of it. It's the only example I've seen like this before.

This white ironstone tablespoon measuring cup can measure out up to four tablespoons,  and would have been used either in the kitchen or with medicines. The number 15, in black typographyon the front of the cup, looks particularly nice. I'm unsure what this number would have symbolised.

On the underside is a mark for well respected ironstone producers, W Adam & Sons.

In fair condition, it has suffered a small amount of damage in its time although it is still a very attractive display piece and is still a very usable piece. It has clearly suffered a fall in its lifetime as there is a chip to the top rim, with a tight hairline beneath it. There is also a hairline on part of the base rim. Despite this wear, though, it is stable - showing the strength of ironstone as a material. 

Height, 6.3cm; Width, 7.5cm; Depth, 7cm