Neil Gaiman has announced that he is adapting Good Omens — the novel he wrote with Terry Pratchett — into a six-part TV series. The author revealed the news during a memorial event for Pratchett in London last night, reports The Guardian, explaining that he had previously been against adapting the 1990 work by himself as the whole novel had been a collaboration between the two writers.

"Terry and I had a deal that we would only work on Good Omens things together," said Gaiman of an initial proposal to adapt the work. "Everything that was ever written — bookmarks and tiny little things — we would always collaborate, everything was a collaboration. So, obviously, no."

This changed when Pratchett's longtime friend and assistant Rob Wilkins presented Gaiman with a letter from Sir Terry written before his death. It said that Gaiman should write the adaptation solo, with Pratchett's blessing. "At that point, I think I said, ‘You bastard, yes,’" said Gaiman.

Good Omens was already adapted for radio back in 2014, with a production for BBC Radio 4 featuring cameos from both Pratchett and Gaiman. However, a number of film and TV adaptations of the novel have fizzled, including a 2002 project directed by Terry Gilliam. This was set to star Johnny Depp and Robin Williams as Crowley the demon and Aziraphale the angel — an unlikely pair of friends who team up to stop the apocalypse taking place in a tiny English village.

According to The Guardian, updates and new of a number of other adaptations of Pratchett's work were also shared during the memorial event. Work continues on a fantasy police procedural based on the adventures of the Ankh-Morporkh City Watch; Rihanna Pratchett (daughter of Terry) is adapting 2003's Wee Free Men into a feature film; and screenwriter Terry Rossio (known for hits including Shrek and Aladdin) is writing a film version of Pratchett's 1987 novel Mort.