Being perfectly honest, I think it's just a blodge of some sort, near where a die letter would be. This happens a lot, and I've often pondered over worn coins wondering if this is a die number, or that is an overstrike etc.
Stuff to make you laugh? Watching Pointless whilst eating tea this evening, one of the questions was anagrams of TV shows. Only 90 people out of 100 were able to identify QI as one of the answers.....
Doesn't seem to be the correct reverse for a Die Letter C... No Die Letter = Reverse G (EXCEPT for a few VERY RARE specimens with Reverse E without Die Letter Die Letter A (All Types) REVERSE G Die Letter B REVERSE E Die Letter C (All Types) REVERSE F See images as follows