Class 3c was the last to be issued at the provincial mints; the subsequent class, 3d, being issued at London, Canterbury and Bury only. These post-provincial phase 3d coins have been sub-divided by Churchill & Thomas (2012) into sub-classes 3d1 and 3d2.  Sub-class 3d2 differs from 3d1 in having a different style of letter R than 3d1 (Ball-shaped foot, R2,  versus a wedge shaped R1) and a broader bust more like that of class 4 coins.   3c coins from non-provincial mints can be distinguished  from 3d1 by the shape of the bust; with busts of sub-class 3d1 being smaller, neater, and with a more pointed chin.  3d2 are relatively easy to identify - their busts being similar to those of class 4, they have the diagnostic ball-footed R, and additionally the inner circle on the reverse tends to be made of smaller pellets, thus allowing a greater number in each quadrant. Prior to the publication of the Churchill and Thomas study, all the above were usually described as 3c, sometimes being sub-divided into 3c early and 3c late.