Pimm's Cup
From The Webtender Wiki
The Pimm's Cup is a highball consisting of Pimm's and either ginger ale or lemon lime soda. It's traditionally garnished with a slice of cucumber.
The Pimm's Cup is a typically English summer drink. In essence, this drink is a kind of gin sling, since Pimm's No. 1 is gin based.
Recipe from the Pimm's bottle label
Fill a tall glass halfway with ice. Add 1.5 oz of PIMM'S. Top off with ginger ale or lemon-lime soda. Garnish with a slice of lemon.