In the base of a cocktail shaker, muddle three cucumber coins with the Lemon Simple Syrup. Add the Pimm’s No. 1 and two ice cubes, and shake for at least 30 seconds, until the shaker is frosty. Line the inside of a tall glass with the length of cucumber garnish, pile high with ice, and pour in the contents of the shaker. Top the glass with the ginger beer and serve with a candied lemon peel left over from making your simple syrup if you like.