I just won this coin -- "A rare variant with the pellet either at the end of the more normal PLON mintmark or at the end of the reverse legend."
Constantine I
A.D. 324-5
19x21mm 3.3g
CONSTAN-TINVS AG; Laureate head right.
PROVIDEN-TIAE AVGG; camp gate with two turrets and star between them, • in bottom of doorway.
in ex. PLON•
RIC VII London 294 variation; LMCC 10.02.002 (this coin cited and illustrated)