This is a number that was assigned to two different shapes during the course of the Early Series years. In this case, both shapes appear in the same shape book which confirms that numbers were indeed sometimes re-assigned.
Shape book 'C'
180(Early Series) Conical vase with wide mouth, slightly flaring.
Does this shape appear in other series? No - (none recorded in image database).
Only one size appears in the shape book and the image database, although the inch suffix '6' seems to imply that there could be others.
Height; 14 - 17 cm
The shape-book entry shows both shapes.
The crossing-out clearly indicates that the lower 180 shape post-dates and supersedes the one above it.
No numbered example is yet recorded in the image database The shape book shows three sizes; small, about 11 cm; medium, about 22 cm; and a very tall size, 180/12 (appearing elsewhere in the same shape book) about 30 cm.
Does this shape appear in other series? Yes - the middle size is like Pamela 31.