Watch List notes:

Constans (337-350). Æ Centenionalis (23mm, 4.44g, 12h). Rome(?). Diademed and draped bust r. R/ Emperor standing l., holding phoenix and labarum, on galley l., steered by Victory seated at r.; A/[...]. Cf. RIC VIII 152 (Rome). VF
Estimate: 10 GBP