Tacitus. Antoninianus. Rome mint. 275-276 AD. 

Obv: IMP CM CL TACITVS AVG, radiate, draped, cuirassed bust right
Rev: VICTORIA AVG, Victory standing left, holding wreath and palm.
Mintmark XXIA.

Ref RIC V-I, 97
(rated common)

Found in England by metal detector.
Contributed by Andy Muller, April 2010.