Watch List notes:

BRITISH COINS, Charles I, Silver Halfcrown, Tower mint, group III, type 3a1, king on horseback left with upright sword of short length and sash flowing from waist, initial mark tun (1636-1638) both sides, rev crowned quartered oval shield of arms with garnish, 14.81g (N 2209; S 2773). Flan a little irregular, minor surface flaws and tiny marks to obverse, very fine, attractively toned.
from the David Sellwood collection

Estimate: £200-250