Great Britain. Crown, 1551. S.2478; Dav-8245. 

Edward VI as equestrian right, date below. S-2478. 
The first dated English coin! 
Mintmark "Y". 

Courtesy Ira & Larry Goldberg Auctioneers, Beverly Hills, CA. www.goldbergcoins.com
Sale 31: The Pre-Long Beach Auction May 30 - June 1, 2005
Lot 2115