Here we have two varieties of the halfpenny.

RACS ½d
Class 1) D with dot underneath
ROYAL A.CO·OP SOCY· / ½D/. 19.8mm
Class 2) D with 2 dots underneath
ROYAL A.CO·OP SOCY· / ½D/.. 19.8mm
Class 3) D with high dot underneath level with hyphen
ROYAL A.CO·OP SOC / ½D/.. 19.8mm
small [normal] dot
Class 4) D with high dot underneath level with hyphen as above
large dot at bottom