If you're going to celebrate the London Olympics (and don't have $3,000 for an Olympian cocktail), than why not celebrate with a London Dry Gin cocktail? BULLDOG London Dry Gin created London-themed drinks in honor of the Olympics; and this one -- the Purple Rain -- honors "the most reliable part of London weather." With champagne, creme de violette, and elderflower liqueur added to the mix, the Purple Rain has the botanical flavor of BULLDOG.
Combine ingredients (save sparkling wine) in a shaker over ice. Shake and strain into a tall glass and top with champagne or cava.