Watch List notes:

British Coins, John (1199-1216), a partial brockage of a penny, short cross, type 5, London, Willelm B, obv. legend present but portrait missing, rev. WILLELM B ON LV, wt. 1.24gms., very fine, rare and unusual
*ex Baldwin's vault
Willelm B is recorded as a moneyer for types 5a-5c.
Estimate: 100-120 GBP