Watch List notes:

BRITISH COINS, Stephen, Silver Cut Halfpenny, Awbridge type, BMC type 7, Castle Rising mint, moneyer Hivn, crowned facing bust with sceptre, STIEFN, rev voided cross limbs within beaded quatrefoil, lis in each angle, +IVN[]SIN, 0.66g (N 881; S 1282). Toned, about extremely fine and extremely rare, even as a Cut Halfpenny.
found in Weston, Hertfordshire, EMC entry 2009.0263

Estimate: £400-500