It's not every day that you find yourself wandering around a Glasgow suburb on the first day of spring walking an author's dog. But such was the case when I met Martin Stewart, the

supremely talented chap behind Riverkeep, a thoroughly exciting new YA debut from the Penguin Random House stable. It's an incredible, accomplished piece of work, a Tolkien-ish epic

about a young boy called Wull who starts the book poised to succeed his father in the position of Riverkeep (essentially the vast river's caretaker) but when his father is possessed by

something from the water's depths Wull finds himself tasked with an even greater challenge. Riverkeep is a triumph on multiple levels and a lot of its success can be attributed to

that he was inspired by the real life Glasgow rivermen who, like Wull and his father, have been fishing out more than shopping trollies and plastic bags. Was it an idea he had long in

gestation? "No, I knew nothing about it," he says. "It wasn't me specifically thinking there was a novel in it because it genuinely was only a short story and only ever

meant to be a short story. It was an article in a newspaper supplement - Scotland on Sunday - a few years ago and I read that, and it was about George Parsonage of the Glasgow Humane

Society". "I took him some Hob Nobs by way of seeing if he would let me into his house, which is right on the Clyde - he still lives in the boathouse." "He told me

stories about life as a riverman. There's a part of you that's interested in the gruesome parts; 'what's the most minging thing you've ever pulled out of the

river?' type of questions. Some of them are in the book - a skeleton half-buried in the ice and picked clean: a true story. I honestly couldn't have imagined this stuff." I

ask if his visit was the sole catalyst for Riverkeep. "Specifically, it was realising that George had been doing this sort of thing since he was 14, which is unbelievable," he

says. "I couldn't do it now as an adult man and to do these things, like Wull, with your father when you're still a child! That was the thing that made me realise - and by

this point I had been reading Patrick Ness and the Northern Lights, and being a teacher... it helped me find my own voice." The practical origins of Riverkeep are as fascinating as its

creative roots. As the proof copy - the cover of which brackets Stewart with the likes of Ursula le Guin, Philip Pullman and Dickens in a not an entirely unfair comparison - explains, the

author nabbed a book deal off the back of a 2000 word story he wrote. Those 2000 words went on to become chapter one of Riverkeep. "So, it was first a short story I had written for

Simon P Clarke's blog and just left it there, basically, and hadn't thought anymore about it. I had a middle-grade book and my agent, Molly Ker Hawn, and I were working on that

with publishers, seeing whether we could sell that. In the process of doing that somebody had asked, "does he have anything else?" and unbeknownst to me she had handed over this

short story I had written. It was another publisher who made an offer on that to have it turned into a novel, which was a total surprise." "I was obviously hugely keen to take that

deal immediately and my agent, who knows more about these things than I do, said, "no". And I was going, "what?!" Obviously, you can imagine, I had been trying to do

this for 10 years. She went back to a bunch of other publishers, one of whom was Penguin and Amy Alward." "It's a mind-blowing thing. On the Penguin website I'm next to

Robert Louis Stevenson on the list. I'm not saying I'm as good as Stevenson but..." We leave Waterstones to rescue Stewart's magnificent dog, Hugo, from the boot of his

car and continue the interview on foot, Hugo in tow. I mention Stewart's incredible knack for description to him. "There's a Neil Gaiman line for that kind of thing where he

said that the best stories - and I really subscribe to this - are the ones that feel true in a way facts could never really be and they feel like they've existed forever," he says.

"Take Coraline, when you read about the Other Mother, that feels like a thing we all instinctively recognise - that's exactly what I hope for." It is clear where

Stewart's inspirations lie, both through speaking to him in person and in reading Riverkeep itself. We end up discussing them. "A Monster Calls was a big inspiration for me,"

Stewart says. "It was so unexpected, I picked it up and it really knocked me for six. The Knife of Never Letting Go was also so high concept - I asked him about this at an event for The

Crane Wife, about how he managed something so strongly conceptual, how do you know that the noise isn't getting annoying? It's such a difficult thing to judge, whether it intrudes

on the narrative." Another thing that stuck out to me in Riverkeep was that it's briefly mentioned that Wull is non-white. Racially diverse fantasy protagonists can be hard to

come by so I thank Stewart for his inclusivity. He's entirely aware of the potentially problematic nature of including solely white characters in fantasy. "I am utterly square in

the middle of the privilege sweet spot," he says. "I'm a white male with a broadly middle class upbringing. I am aged 25-40. Being a teacher and coming into contact with the

various challenges a lot of young people live with, I had an extremely cosy upbringing. I am hugely aware of all the privilege that I'm writing from." "What I tried to do with

the book, as much as I could, was write from a post-racial and slightly post-gender point of view. It's my first book; a lot of authors would agree you put so much of yourself into

these. My grandpa became very unwell and needed a lot of looking after by my gran, he had a bit of dementia, and it changed him - he was largely absent of the man he had been, basically.

That was the thing that affected me that is in this story. That was quite a personal thing. Dealing with that, I was 28 at this point, there are young people who are 10 years old dealing

with that in a much more immediate sense, when it's a parent or somebody and they have to look after them. I've never had to deal with that kind of hardship but it's something

I wanted to tackle. I've worked in schools where there have been a lot of young carers, they go through more than you can imagine. It's a heroic thing that they do and that's

something I wanted to pay tribute to." Going back to racial diversity, Stewart is confused by the amount of white protagonists there are. "When you have this massive spectrum of

choice, why you would go for that heteronormative..." he tails off, shaking his head. "Wull's ethnicity is non-specific, which was really intentional. He's got

non-specific ethnicity but he's got dark skin. That was something that I wanted to make sure. I wanted characters - including my protagonist - who presented a spectrum of racial

diversity but simultaneously making it literally nothing to do with the plot at the same time." Stewart has already snagged himself another book deal, which he's in the process of

writing now. I ask him what his writing process is like. "With Riverkeep I was on a very short deadline. I started writing Riverkeep properly in January 2015, the first draft took me

six weeks and then I spent two weeks editing before sending it to my agent. It's been different this time. I had more of a strict rhythm and because my characters were on a journey it

was easy to go along with the journey." "It's a group of five young people this time. There's our main protagonist but he's in a group of five so the dynamic is

different compared to Riverkeep." I ask if it's in the same genre as his first book. "Ish," he says. "What do you think the genre of Riverkeep is?" Fantasy, I

hazard although it doesn't seem like an accurate description. "You see, I don't think it is fantasy. I think fantasy is a slightly silly term. To me, the best stories have

something a little bit strange and macabre and other about them. I've read books that are a lot more realist and I've read non-fiction but to me my gut instinct whenever I think of

a story is 'okay, but what if there were zombies? Okay, but what if the house were haunted?' You throw in something - it's an instinct for genre fiction that I have." *

Buy Riverkeep at the Guardian bookshop