Carausius, AE antoninianus. Uncertain mint. 

VIRTVS CARAVSI, Radiate, helmeted, cuirassed bust left, 
holding spear and shield.
ADVENTVS CARAVSI, Emperor on horseback, riding left,
holding sceptre, raising right hand

RIC V-2, uncertain British mint 735
Very rare (R3).
Found in Hampshire GB.