Constantine I. AE4, Lyons.

CONSTANTI-NVS MAX AVG, laurel and rosette-diademed, 
draped and cuirassed bust right.
GLOR-IA EXERC-ITVS, two soldiers holding spears and shields 
with one standard between them. O on banner.

Mintmark: star PLG.

RIC VII Lyons 280, rated R4.

Note: RIC lists only "rosette diademed", but on this
coin it is clearly a laurel and rosette diadem with () shaped leaves between the rosettes. 
Coin found in England.

From Dane's collection, August 2010.

Known mintmarks for this RIC number:
star PLG
star SLG