Watch List notes:

UNCERTAIN WESTERN EUROPE. Æ As (27mm, 11.08 g, 7h). Countermark applied mid 1st century AD . (MV?) in rectangular countermark on a bronze as of Caligula (RIC I 54). Apparently unpublished in the standard references. Host coin VF, c/m VF, brown patina.

From the Richard Baker Collection.

This enigmatic countermark can perhaps be interpreted as an imitation of one of the common AVC or IMP stamps, struck over an official issue.