"Shada", a Doctor Who serial from 1979 starring Tom Baker, was written by the late great Douglas Adams. A strike at the BBC meant that the recording was never completed, so for the best part of 25 years it remained unfinished. In the intervening time, Douglas Adams borrowed several elements from the serial and wove them into his novel "Dirk Gently's Holistic Detective Agency", which sees the eponymous hero and Professor Chronotis go back in time and meet the Dodo. Adams also refers to the history of the Dodo in his book "Last Chance To See" of course.
A few years ago, the Big Finish company remade "Shada" as a BBC webcast (audio plus animation) starring Paul McGann as the Eighth Doctor, with K9 and Lalla Ward as Romana. Incidentally, Douglas Adams introduced Lalla to her future husband (the scientist Richard Dawkins) at his 40th birthday party in 1992.
The story was then released on CD by Big Finish, and for this week only, the BBC's digital radio station BBC7 is broadcasting a compilation of the 6 part adventure.
You can LISTEN FOR FREE until Friday 16th December. The full BBC7 Saturday schedule can be seen here.
The broadcast features a rather nice prologue, in the style of a famous paragraph from "The Hitchhikers Guide To The Galaxy".