WHEN Catherine Simpson’s daughter read her mother’s debut novel – which is inspired by her elder sister’s autism – Lara Mega said how much she liked the book before adding, “You said that Truestory wasn’t about Nina, but Nina is on every page.”

Seventeen-year-old Lara was right, of course, acknowledges Simpson. For, although Truestory centres on 11-year-old Sam and his mother’s lonely, often despairing struggle to cope with a child suffering from undiagnosed Asperger’s Syndrome, it’s 20-year-old Nina’s story that has informed Simpson’s enjoyable first work of fiction.

Now reading German at Edinburgh University, Nina echoed her sister’s opinion, telling her mother that she approves of the book’s portrayal of autism, but doesn’t like the ending. That meant the world to 51-year-old Simpson, because, her “bright, beautiful” daughters – their father is Edinburgh-based investigative journalist Marcello Mega – are “the two most straight-talking women there are”. As is their vivacious mother.

Set on an isolated dairy farm in Lancashire – Simpson was born and grew up on such a farm – Truestory is most definitely not an everyday story of country folk. It is dedicated to Simpson’s younger sister, Tricia, who suffered from depression and committed suicide last year, after taking on the running of the family farm. “It was a terrible, terrible shock. Such a tragedy,” Simpson says, adding that her 89-year-old father, Stuart, is farming again, although he’ll be in Edinburgh for her launch party on Thursday.

“Dad’s always been my inspiration," she says. "I think he’s proud I’ve finally got a book published -- I wrote my first when I was eight.” He certainly ought to be proud since her sharply observed novel is a terrific read. Narrated by Alice, who is trapped, emotionally, geographically and financially, it tells how her husband, Duncan, is in denial about their troubled son, while their farm is failing.

In his local, Duncan meets the handsome, charming Larry, and brings him home to help with his latest money-making scheme. Despite Sam’s dislike of change, he and Larry forge an unlikely friendship, while Alice bonds, in rather earthier ways, with this sexy stranger. “I have to stress this is not autobiographical,” laughs Simpson. “I have never had sex in a polytunnel with an itinerant worker.”

The novel is interspersed with pages from Sam’s online chat-room conversations. His user name is Truestory, explains Simpson, because when an autistic person becomes convinced that something is true, there’s no arguing otherwise. Home-schooled by Alice, Sam refuses to venture more than 823 steps from home, will eat only 19 pieces of pasta for tea, is disturbed by loud noise and the colour yellow, and is obsessed with maps.

Always, while writing Truestory, Simpson was aware of the canine in the room, namely Mark Haddon’s mega bestseller, The Curious Incident Of The Dog In The Night-time, in which although it is never specified, it’s clear that the 15-year-old protagonist has Asperger’s. “I rewrote and rewrote Truestory to ensure that no one could say it was ‘another Curious Incident...’ I honestly can’t think of a novel that deals with autism from a parent’s points of view. Kathy Lette’s The Boy Who Fell To Earth is based on her son’s condition. It’s a very different book to mine, which is about what you owe your children – and at what point do you martyr yourself?

“Like many journalists, I’d always dreamed of writing a novel – Marcello’s writing his now,” continues Simpson, whose career has taken her from the civil service to gaining a degree in communications studies as a mature student at Birmingham University.

“After wanting to be a journalist for years, which I did eventually, I decided that I wanted to help people. After we married, I worked briefly for a children’s charity – ironically, the Scottish Society for Autistic Children. Before the interview, I researched autism because I’d never heard of it. I remember sitting in Edinburgh’s Central Library reading that mothers were ‘to blame’ for their child’s autism. They were ‘refrigerator mothers,’ who had created the autism in their children because they hadn’t given them any love.”

After Nina’s birth, Simpson knew there was something wrong with her daughter. “No one would back me up. She was crying all the time, refusing to play or communicate; I couldn’t make her happy. Nobody would listen to me. It actually made me feel slightly insane.”

Eventually Nina was referred to the Sick Kids hospital in Edinburgh, where the specialist laughed in Simpson’s face. “Treat your child differently, she will act differently,” she was told. “It was back to the ‘refrigerator mother’!” Nina was 10 before her condition was finally diagnosed and, at 14, moved to a school where she wasn’t mercilessly bullied. Soon, she departs alone for Berlin as part of her degree course.

Now working with Art Link, the disability charity and arts organisation, Simpson is currently compiling a report for Midlothian Council on autism, and has so far interviewed some 25 children and parents. “So many people who share in one way or another my experiences with Nina!” she exclaims. “If only I’d met people like that years ago.

“When Nina was a toddler, I’d go to mother-and-baby groups but no one wanted to know me because Nina would snatch another child’s toy, or start crying without stopping. Like Sam, she hated loud noises so I wheeled her endlessly around charity shops. Once, an old lady shouted at me that I was a bad mother because Nina was screaming her head off – an incident I used in Truestory. I got deeply depressed, felt lonely and helpless, because, obviously, Marcello had to work.”

Already writing her second novel, Simpson accepts that some might accuse her of exploiting her daughter’s life. “Truestory is certainly inspired by her but it’s definitely not based on her and she was aware I was picking her brains. She’s actually in the book twice – one chat-room character is Fizzy Mascara, which she used to call herself on some forum or other. Yes, I definitely nicked that.”

Truestory by Catherine Simpson is published by Sandstone Press, priced £8.99