At long last. Douglas Adams wrote the wonderful The Hitchhiker's Guide to the Galaxy radio/tv series/novels, but also a couple of existential science/philosophy detective novels featuring Dirk Gently which have been crying out for a television version for decades. This is why I pay my licence fee.
BBC4 will also dramatise Adams's 1987 novel about anti-hero Dirk Gently next year. Adams was writing a third Dirk Gently book, The Salmon of Doubt, at the time of his death in 2001.