Conway Stewart made lots of different variants of the 540 "DINKIE", starting in the 1920s up to 1942, in many different colours, with flat tops, domed tops and peak tops; with ring tops, cap clips or none at all.  This example was certainly made late in that period. Finished in blue, it is without clip or ring top. The imprint reads "   "DINKIE"  Conway Stewart London   No 540". A second imprint around the barrel is very shallow but can just be read: " MADE IN ENGLAND".  It has a small filling lever terminated with a round shield, with an intertwined "CS".  The ink sac has been replaced. The clipless cap has a black peaked top and a single gold plated cap band.  There is a slight colour mismatch between the cap and barrel.

The nib is stamped "Conway Stewart  14CT  GOLD". The medium nib is in good condition, and despite the difficulty I had in testing it (holding a very small pen held in biggish hand), I can confirm that it writes well.