9 ways Amazon's Good Omens TV series is different from the book

*WARNING: spoilers ahead for Amazon's Good Omens*

However, in any screen adaptation there are going to be changes, and Good Omens is no exception: there are some welcome additions (we're looking at you, Jon Hamm), some characters left on the cutting floor, and an incident during the finale involving a bathtub of holy water...

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• Everything you need to know about Good Omens

Read on for the most significant changes between the novel and Amazon's TV adaptation, starring Michael Sheen and David Tennant.

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1. Was Aziraphale and Crowley's backstory in the Good Omens book?

Episode three opens with "the longest cold open in the history of television," according to David Tennant, as we follow Aziraphale and Crowley's burgeoning friendship dating back from the Garden of Eden, with glimpses of their lives in the following centuries, including various Biblical scenes, Shakespearean England and 1960s Soho.

"I've got a favourite bit. Which is the first half of episode three," Tennant said in an interview with RadioTimes.com. "It's the longest cold open in the history of television. It's the first half - I think it's 31 minutes before the titles come up."

"Which is not in the books as well," Michael Sheen added. "So that's something that people won't have seen before."

"Though there are moments in the book that allude to some of the scenes that he's [Neil Gaiman] fleshed out," Tennant continued. "So he starts in the Garden of Eden and then you see them in about 10 different scenes through history, which is a sort of potted history of their relationship and a potted history of the world. All in 31 minutes."

2. Where are The Other Horsemen in Amazon's Good Omens?

In the Good Omens novel, four Hell's Angels bikers meet the real-life Four Horsepersons of the Apocalypse at the Happy Porker Cafe, and decide to tag along for the ride — only to collide with a motorway pile-up of fish.

Although The Other Horsemen remain fan favourites among readers, Neil Gaiman has explained why he cut the bumbling riders out of the series, in an interview for the show's accompanying book, The Nice and Accurate Good Omens TV Companion.

• Watch Good Omens with a 30-day free trial for Amazon Prime

"Terry died and left me, and this was his last request," Gaiman said. "My job is to make this something he would be proud of, and sometimes that meant I'm more likely to hold my position on a thing that Terry wrote than something I wrote.

"In this case, I was willing to lose The Four Other Horsemen from the script, a week before shooting, for budgetary reasons. I looked at the script and thought, I can pull it out and it does no harm. Even though some people will be disappointed, my response is that it's still in the book."

3. Does Crowley have red hair in the Good Omens book?

The fast-living demon Crowley is described as having "dark hair" in Neil Gaiman and Terry Pratchett's original novel, but David Tennant has explained how Amazon's costume and make-up department first conceived of Crowley's now-signature (and ever-changing) flame-red locks.

"It wasn't in the book, but red seemed quite appealing as he's from the flames," he said. "There's also a part of me as an actor who likes to transform."

"We talked about whether having it long might make him look like a rocker, rather than of the moment," Tennant said in an interview for the show's accompanying book, The Nice and Accurate Good Omens TV Companion.

• David Tennant explains why Crowley has red hair in the Good Omens TV series

"Eventually we settled on a nice, short funky red cut. Then we see him moving through time with different lengths and styles. When I was reading through the script, just plotting through what happens when was quite tricky, and so it works as a marker."

4. Does Agnes Nutter write a prophecy for Aziraphale in the Good Omens book?

The Nice and Accurate Prophecies of Agnes Nutter is the one book that the bibliophile angel Aziraphale has always coveted, but never acquired — that is, however, until fate takes a hand and the ancient tome lands in his lap (or, more accurately, in Crowley's 1926 Bentley).

It seems only fitting then that Agnes has written a prophecy for the angel, correctly describing him sitting in his store filled with books "written by other men," before warning him that... his cocoa his growing cold. As he reads the prophecy, Aziraphale looks over and, lo and behold, his cocoa is growing cold right then and there.

• Neil Gaiman: Agnes Nutter was almost cut from Good Omens – but I couldn't do that to Terry Pratchett's creation

It's a brilliant moment, made all the more memorable given that it's not actually in the book. In the original novel, the angel made cocoa and "read a prophecy at random." The original passage continues: "Forty minutes later, the cocoa was still untouched."

5. Where is the ducking stool in Amazon's Good Omens?

In the Good Omens book, Pepper's six-year-old sister is enlisted by the Them (the group of kids led by Adam Young) to play a witch in a 'torture' game involving a ducking stool — which the other children then beg to have a turn on. However, the scene was apparently cut due to health and safety issues, replacing the makeshift ducking stool with a tyre swing.

In an onset interview with RadioTimes.com, Michael Sheen (Aziraphale) admitted that he regretted the scene's absence in the show.

"There is only one moment that I wish was in it. I just makes me... I just think it's wonderful," he said. "And you can't do it because of health and safety."

• Amazon's Good Omens review: "A devilishly funny love letter to the book"

Adding that he'd concealed his feelings about the scene from showrunner Neil Gaiman, Sheen explained: "I never actually told Neil that... I wanted it, because I felt so bad because he explained to me one day and said, 'Oh we can't do that. So we're going to do this instead.' And I was so disappointed, and I couldn't tell him because I didn't want to upset him... But it's the moment where the children are trying to torture the witch and they've got a ducking [stool].

"In terms of the book it cuts back and it's this tiny little girl, it's Pepper's sister I think, who's just sitting there, really enjoying it, and the whole point of it is that it's torture, and they cut that. Apparently you can't dunk little kids! It's terrible. It's such a great cut for TV as well."

6. Is Jon Hamm's character Angel Gabriel in the Good Omens book?

Jon Hamm's corporate-minded Angel Gabriel is only mentioned very briefly in the original Good Omens novel. But the role was expanded for the series, alongside a host of other angelic characters – and this version of Angel Gabriel is a fan of tailored suits and The Sound of Music (but not a fan of sushi).

Speaking to RadioTimes.com on-set, Neil Gaiman explained that he and co-author Terry Pratchett had always intended to flesh out the characters in Heaven.

"One of the things that I did in Good Omens as well, partly to open it up a little bit, but more because Terry and I had planned to do this 30 years ago, was actually bring on the angels," he said. "We go to Hell, we see some more stuff that happens there, we learn more. In the book, angels are basically talked about but almost never seen, and we have a couple of demons. In this, there is equal time."

• Jon Hamm’s Good Omens character Angel Gabriel was originally British

"Gabriel is barely in the novel," Hamm said in an interview for the accompanying book to Amazon's Good Omens, The Nice and Accurate Good Omens TV Companion. "But he's fleshed out here because Neil Gaiman wanted someone cracking the whip. So he's the guy from head office who is like, 'Hey, what are you doing? Go to work!' As a narrative device it's very funny, and the fact that I get to do it is awesome because originally he was written as British."

Initially, as the Mad Men actor explained, Archangel Gabriel was imagined as “that stuffy, posh Brit who can’t get out of his own way.” But Gaiman soon changed his mind.

“Neil felt he should be from the USA, and that made sense to me,” Hamm said. “The idea of the American walking in and saying: ‘We gotta do it my way!’ is very easy for me to inhabit.”

7. Do we see Heaven and Hell in the Good Omens book?

Just as the TV series of Good Omens expanded on its host of angelic characters, the show also went into greater detail about the appearance of Heaven — and of Hell.

Of the pristine, heavenly headquarters that formed Heaven, location manager Nick Marshall said: "We found a vacant office building in a smart business park in Weybridge, Surrey. It had a tiled floor, white pillars and 13 floor-to-ceiling windows. We had to frost every single one of them to get the light looking celestial."

"It really did have a heavenly vibe," he added, said in an interview for the show's accompanying book, The Nice and Accurate Good Omens TV Companion.

Meanwhile Hell is depicted as a dingy, cramped basement office, strewn with litter and mismatched plastic chairs. "God and the angels got the pick of the best place," said producer Phil Collinson, "while the demons go down into the basement. Hell is like a struggling business that can't afford bigger premises."

8. Is there the fire and (holy) water scene in the Good Omens book?

Neil Gaiman wrote an additional twist for the Good Omens finale, which saw both Aziraphale and Crowley kidnapped by their respective celestial peers. They were both sentenced to death: Aziraphale by infernal fire, and Crowley by a bathtub of holy water.

However, following a final cryptic prophecy from Agnes Nutter, the pair had the foresight to switch bodies. Neither perished — in fact, Crowley/Aziraphale had a rather lovely dip in the bath — and both managed to convince the forces of Heaven and Hell to leave them alone (at least for a bit).

Speaking about the ending in an exclusive on-set interview with RadioTimes.com, Gaiman said that he altered the original ending as he didn't want viewers who'd read the book to get "too cocky".

"There's a couple of places I took liberties, and I took some liberties in the end because I didn't want people who read the book being too cocky. So there is stuff that keeps ticking and will keep worrying them and a plot that does not untangle until the final second, and that was fun to build," he said.

9. What happens at Warlock's birthday party in Good Omens?

When Aziraphale dresses up as a children's entertainer for Warlock's birthday party, his terrible attempts at human magic have rather more dangerous consequences in the book than in the TV series...

In the novel, Aziraphale asks a security guard to pull a silk handkerchief out of his pocket, which catches on the guard's gun and sends it "spinning across the room to land heavily in a bowl of jelly". Warlock, an obnoxious eleven-year-old, grabs the gun and fires it at Crowley.

However, Aziraphale manages to turn the Magnum .32 into a water-pistol, saving Crowley from a rather inconvenient "discorporation". Aziraphale also has a spot of bother with a dove stuffed up the arm of his frock coat for too long, which Crowley then revives.

In the TV series, however, the gun-in-jelly fiasco is entirely cut, while the dove is actually revived by Aziraphale — a switch that was down to logistics, according to Neil Gaiman.

"The Good Omens fans are just obsessive, in basically a very nice way," Gaiman told RadioTimes.com, "but there was a moment on the screen when you saw Aziraphale after a children's party with a dead dove in his hand, and I posted a tweet saying, 'Today, Aziraphale will bring a dove that had been shoved up his sleeve and it died back to life'.

"And people were like, 'In the book, it's Crowley who...' and we were like, 'Yeah, but we couldn't do that because... we have a Bentley in the way, physically, and Crowley has to get... and he's still standing, so...'"

Good Omens airs on Wednesdays at 9pm on BBC Two