Constantine I AE follis, 310-312 AD. London.

Obv: CONSTANTINVS AVG, helmeted and cuirassed bust left,
spear over shoulder, shield on left arm.
Rev: ADVENTVS AVG, Constantine on horseback, riding left, 
right hand raised, left holding spear upwards, horse pawing 
seated captive to left.

Star in right field.
Mintmark PLN.

RIC VI Londinium 141 var (unlisted bust type for this series).

Courtesy of Chip Gruszczinski, Aug, 2010