Rather than the art they had previously been practising, Alex instructs her troubled students to study the Greek tragedies of 5th century playwrights like Euripides and Aeschylus. Having specialised in the subject at school and university, Haynes has previously explored the impact the Greeks have had upon contemporary society in her 2010 non-fiction book, The Ancient Guide To Modern Life.
"I always have to say that nobody in the novel knows as much about the classics as I do," she says. "That includes Alex, who is usually about three weeks ahead of her pupils, which is something a lot of teachers will often admit to being."
But although both her own parents were teachers, Haynes was never tempted to enter the profession herself. "Lots of people have asked me 'why not?' but have you seen what teachers have to do? It's really hard work, so big respect to teachers. When the book first came out, I was asked whether they should actually do that in pupil referral units, but I couldn't possibly say. That's up to the people employed in those places, as I'm not going to tell them they're not working hard enough. I imagine they already do the absolute most they can, because everyone I've ever spoken to who works in a PRU is just the most committed, passionate supporter of children you could ever hope to find."
Edinburgh has been described as looking like it was designed by Escher. No matter in what direction you turn, you always seem to have to go uphill.
Instead of teaching, Haynes turned to journalism and has since written for newspapers such as The Times and The Independent as well as regularly appearing on BBC Radio 4 and as a resident critic on the BBC Two's now-defunct Review Show. Seemingly desiring to keep her options open, she was also a stand-up comedian before retiring from performing in 2006. "It always makes it look like I'm in constant need of stimulation when, in fact, I just like to pay the bills," she says drolly.
Handily dubbed the Athens of the North, it was the five increasingly fraught seasons Haynes spent putting on shows at the Edinburgh Festival Fringe that helped her to settle on the Scottish capital as the location of her novel. "I'd like to claim that as a clever reference but I'd actually forgotten it was called that until somebody mentioned it, about a month before the book came out," she admits. "But I wanted somewhere where things like the geography and the weather would reflect the tone of the book. Edinburgh has been described as looking like it was designed by Escher. No matter in what direction you turn, you always seem to have to go uphill. I've spent so much time in Edinburgh that I've probably spent about a decade living there altogether so I know it really well."
Although originally from Birmingham, her current hometown of London made for an unsuitable setting, says Haynes. "It needed to be a city you could walk around in a reasonable amount of time. In one sense, the book is about people thinking and meditating as they move about, but if they're in cars or on bikes, the whole thing instantly changes. I wanted people to move at walking speed."
Conceding there is something of herself in all of her characters, Haynes insists she and Alex have very little in common. "I hope that's the case," she says. "But it's always quite difficult - and maybe even impossible - to invent a character who doesn't contain at least some of your own characteristics, because they have, after all, come out of your head. I wrote a children's book called The Great Escape in 2007 and back then everybody said that I was definitely Milly because the heroine in that was 11 years old and a vegan. But then my boyfriend read it and said that I was definitely Max, the cat, so there you go!"
Consequently, the character in The Amber Fury that Haynes believes she most closely resembles is the pupil referral unit's headmaster, Robert, who gives Alex her vital chance. "I'm always trying really hard not to be Annika," she says, referring to one of the PRU's most traumatised residents. "My main aim in life is not to be Annika and I know I'm having a bad day when Annika appears reasonable to me."
• Natalie Haynes will appear at the Auckland Writers Festival, Aotea Centre, May 13-17.