Matt Whyman - The Nice and Accurate Good Omens TV Companion: Your guide to Armageddon and the series based on the bestselling novel by Terry Pratchett and Neil Gaiman

We laughed at the same kind of things, and became friends. Neil and Terry, photographed here in November 1990 at the World Fantasy Convention in Illinois.

Beth Gwinn/Michael Ochs Archive/Getty Images

Terry Pratchett was among the select band who received the opening chapters, and there the story pauses for some time. My graphic novel, Sandman, happened, explains Neil. For almost an entire year, life became about writing that. Then my phone rang. And the voice says: That thing you sent me. I want to know what happens. Are you doing anything with it? It was Terry. I told him I was busy, and he made me an offer. Either sell me what youve done, he said, or we can write it together. And because I am no fool, I told him we would write it together. Why wouldnt I? Terry knows his craft. He had fantasy tied up but nobody was writing funny horror, and here was an opportunity to write a novel with him. It was like Michelangelo asking me if I wanted to help him paint a ceiling.

When two authors collaborate, its often easy to see the joins. While Terry and Neil possess unique voices, Good Omens is a seamless read and this is testament to their talents. Since publication in 1990, readers have continued to debate how the pair created what has now become a classic. Anyone who assumes I did all of the dark bits and Terry did all the jokes kind of misses the point, says Neil. When we wrote the book it was very simple. I had an audience of one for my bits, and he had an audience of one, which was me. The entire game for each of us was, Can I make him laugh or wish hed written that? I read reviews where people assume that I had written a dark and somber story, and Terry had stood behind me tossing out jokes like rose petals, but thats not what happened. The fact is I wrote the opening in classic English humor style, like P. G. Wodehouse, Douglas Adams and Richmal Crompton. I understood it, and so did Terry. Neither of us created it. And then Terry came in, carried on, and I carried on from there. Wed rewrite each others pages, write footnotes for them, throw characters in and hand them over when we got stuck. Ultimately, we wrote a book together. It was all about the phone calls and the writing.

As a measure of just how closely this process drew the strands of the story together, Neil reflects on a moment that occurred during the editing process. We were sitting in the damp, cold basement of Gollancz, our publisher at the time, when Terry laughed at a gag in the manuscript. Thats really good! he said to me, but I swore that he had written it. We came to the conclusion that the manuscript had begun writing itself, which neither of us would admit to for fear of being thought weird.

Just ahead of publication, a minor misunderstanding occurred that would launch the novel on an epic journey to the screen. Keen to share their work with people they admired, Terry and Neil sent an advance copy to Monty Python star, screenwriter and film director Terry Gilliam.

We included a note to introduce the book, Neil explains, and politely asked if he might write a quote that could be used to promote it. Only somehow the note went astray, which meant Terry Gilliam found this book on his desk with no explanation why, and just assumed it was because it might have film potential. So, he read it, and it turns out that he loved it, because the next thing we knew he was trying to buy the rights. Neil considers his words for a moment, as he will several times throughout his account. As Good Omens is a novel that would take almost thirty years to reach the screen, I quickly come to realize that such a pause precedes a setback. Sadly, theres a fuck-up in the negotiations, he continues finally. Terry Gilliam still wanted to do it, but the film rights ended up going elsewhere.

Its here that Hollywood gets involved in the story. While the writing partnership endured under the GaimanPratchett Accord, as Neil calls it, the stateside switch also marked a stint in development hell.

It was early 1991, says Neil. The book had just been published in the USA, and Terry and I were invited out to attend lots of meetings. We were put up at the Chateau Marmont on Sunset Boulevard, which was run down and seedy at the time and is now the coolest of hotels. Every morning we would write new outlines, based on the previous days meeting and in the afternoon we would go and have another meeting with people who hadnt read the outline wed sent to them. It was a strange experience, he recalls diplomatically. Eventually, we said that we needed to go home and start writing a script, which we did. And in putting together an early draft we used characters wed already planned to put in the sequel to