The pattern number for this vase is RSW/110. In the catalogue for the exhibition held at King's Lynn in 2004, the caption under the photograph refers to them as 'Squat Vases'.
They vary in size and shape slightly because they were hand made, so can be broader or slimmer, and inded height varies. I have just taken two out of their 'nesting' place and they measure as 13.7cm and 15cm; the taller of the two has the look of being noticably taller even though there's very little difference - still, could be two sizes. On a quick flick through the books and catalogue there seems to be no mention of the sizes, although Susan Tobin refers to four versions.
It also came in pink and white swirling, from memory.
EDIT: Yep, I was avoiding the wrist breaking Hajdamach, which does indeed have the size! :huh: 5"/12.5cm and 6"/15cm does suggest that either there was a large latitude/tolerance in sizing, or, that there could well be two sizes. N.