Watch List notes:

COMMEMORATIVE MEDALS BY SUBJECT. Engraved Coins, smoothed Georgian Halfpenny, engraved "Sarah Brock" and armorial goat's head to left, 27.5mm; another, with initials IP / SC, 28mm. First fine, the second nearly so but stained and verdigris spot to SC side. (2)
The goat's head is the crest of some branches of the Brook[e] family and, no doubt, also the Brock's.

Estimate: £30-50