The Vesper is the celebrated cocktail invented by James Bond in Casino Royale. The superspy with the license to kill directs a bartender with exactitude:
"A dry martini," [Bond] said. "One. In a deep champagne goblet."
"Just a moment. Three measures of Gordon's, one of vodka, half a measure of Kina Lillet. Shake it very well until it's ice-cold, then add a large thin slice of lemon peel. Got it?"
"Certainly, monsieur." The barman seemed pleased with the idea.
"Gosh, that's certainly a drink," said Leiter.
Bond laughed. "When I'm...er...concentrating," he explained, "I never have more than one drink before dinner. But I do like that one to be large and very strong and very cold and very well-made. I hate small portions of anything, particularly when they taste bad. This drink's my own invention. I'm going to patent it when I can think of a good name."
-Ian Fleming, Casino Royale, Chapter 7, "Rouge et Noir'
It's obvious that the cocktail owes something to its literary roots. According to Wikipedia, the Vesper was created for Fleming by a friend to celebrate Bond.
Looking at the recipe, we see:
- Russian Vodka and British Gin
- The components are famously shaken, not stirred
- Kina Lillet to add a bitter note to the herby Vermouth
It sounds like the sort of thing you might come up with to commemorate a cold-war superspy. It's a literary construct to celebrate the sex-and-death world of the British spy and his Soviet rivals. Well, that's my theory.