A.N. Prior on John Wyndham's case

In his paper “Opposite Number” (1957) A.N. Prior anticipates the later philosophical debate on the ideas of bifurcation in time, existence and identity. The paper was inspired by a science fiction story by John Wyndham, and it was published in 1957, i.e., the year before Kripke´s famous letter of September 3, 1958, in which the idea of branching time was suggested. Which means that important aspects of this idea and complex problems related to it, were discussed by Prior earlier than has traditionally been assumed