The Vesper Cocktail recipe first appeared in 1953 in the James Bond book "Casino Royale" written by Ian Fleming. The cocktail is described there as an invention of James Bond, and which he would have baptized "Vesper" because of his deep attachment to Vesper Lynd, another character in the novel.
Several stories are told about the origin of the cocktail, but the real origin would be in the book "You Only Live Once", autobiography of Ian Fleming written by Ivar Bryce. The author recalls that in his copy of "Casion Royale", Ian Fleming wrote "To Ivar, who mixed the first vesper and said the good word". Ivar Bryce also explains that the name "Vesper" comes from an already existing drink which was served at the house of a British colonel living in Jamaica and which was composed of rum, frozen fruits and herbs.
Lillet is an aperitif made of 85% Bordeaux wine (sauvigon and semillon grape varieties) and 15% fruit liqueur, there are 2 kinds: white Lillet and red. At the time Ian Fleming's book was published, white Lillet was known as "Kina Lillet".