526  (500 Series)   Plump pot, dimpled, wavy rim, no flare.
Does this shape appear in other series?  Yes -  Early Series 402;  Later Series 12.
Only one size is recorded but the use of a size suffix suggests other sizes may exist.

       Height;  10 - 10.5 cm

            Collection; "W"
The same shape in three numbering series.
500 Series 526-5 (centre) flanked by Early Series 402-5 (left) and Later Series 12-5 (right).