Silver Proof £1

Since the introduction of the £1 coin on 21^st April 1983, it has become one of the most collected coins, with specially minted commemorative coins being produced in both Silver Proof and Silver Proof Piedfort edition.
 
Piedfort coins are struck on thicker than normal blanks.  As their name suggests they are closely associated with France, where from the twelfth century they were apparently used by the King as presentation pieces.