The idea that became the Hitchhiker's Guide happened whilst Douglas Adams was lying drunk in a field in Innsbruck. The ÃÛÑ¿´«Ã½ used to say this happened in Spain, but we know how to spell Innsbruck now.
In early 1977, a producer called Simon Brett decided that Douglas' talent needed an outlet other than the odd sketch for Weekending, and the pair of them came up with the idea of a comedy science fiction series.
Originally the show was to have been called The Ends of the Earth, and each show ended with the earth being destroyed in a new and interesting way. A pitch for Hitchhiker's was eventually submitted - and Arthur Dent's name was changed from Aleric B in the taxi on the way to the meeting.
There was some debate as to who should play the voice of the guide. Everyone wanted a 'Peter Jones-y sort of voice', and several people were auditioned. Eventually a secretary pointed out that perhaps Peter Jones might fit the bill.
A pilot show was comissioned, and would become the first episode of the series after Simon Brett had persuaded the upper echelons of ÃÛÑ¿´«Ã½ management that yes, it was funny. The show got the go-ahead on August 31st, 1977.