Picture if you will a nice state primary school, in 1980s south Wales. We had an oak tree. One time a man drove a Sinclair C5 round the playground to show us The Future. We had plenty of undiagnosed dyslexia and NHS specs (frame choices: brown, blue, pink, clear; all pure Jarvis Cocker), but no greater challenges were allowed to enter - so we never thought about them. We didn’t call it segregation. If it had been pointed out, I’m sure I’d have thought it wasn’t anything personal. My experience of people with disabilities was, like most mainstream-schooled kids of that time, Joey Deacon on Blue Peter.

If you remember him too, you’ll know the playground nickname “Joey” was not one of endearment. I clench all over just remembering: pulled faces in the playground, sneers, disgust. Kids can be cruel.

The fiction I read then was kinder - uncomfortably so. Books for eight to 12s are often about growing up, self-discovery, overcoming a challenge. In classic children’s fiction, physical disability tends to be co-opted not only as a cautionary tale, but a completely useless one where it turns out you’ll be ok in the end - so long as you’re nice, or you try hard. The Secret Garden’s invalid Colin apparently only needs a bit of fresh air and gardening to magically regain his health. In What Katy Did, Katy’s spinal injury is a lesson in patience and goodness; once she’s learned it, she walks again.

Skip ahead in time to a modern state school and things have changed. When I trained as a primary teacher (before I realised I was better at making up imaginary kids than explaining what a rhombus is to real ones), I met kids with learning disabilities, visual impairments, communication disorders. I worked very briefly with a boy with complex needs who used a motorised chair and breathing apparatus. On Sports Day. I was afraid - of saying or doing something wrong, of hurting him, and, most pathetically, of looking like a bad able person who didn’t know how to deal with his disability.

My nice oak-tree school hadn’t educated me at all. But his peers modelled how I should act without a second thought; he was a person, with a voice, with opinions, one of them. Including him, with consideration for what he wanted to be involved in, was an automatic part of their school day (clearly developed with thoughtful support from the class teacher). Kids can be brilliant, too.

I’d love to say that children’s fiction has taken a similar leap since the days of the Sinclair C5, but I can’t. The #WeNeedDiverseBooks campaign continues to go from strength to strength, and sites like Disability in Kidlit , and Cindy Pon and Malinda Lo’s Diversity in YA are fantastic resources for authors and readers alike - but these campaigning sites exist for good reason.

There are happy exceptions: Julia Golding’s Young Knights adventure fantasy series features a wheelchair user; Jacqueline Wilson’s wonderful Katy is a retelling of What Katy Did, with a more honest conclusion (you can read a review of Katy by teen site member Writer on Wheels here) But the idea that young people with disabilities (congenital or acquired, physical and/or mental, mild to severe, single or overlapping) might be entitled to find themselves in fiction - not to teach able children to be better people, not to be cured, not to be “issues” but to cast spells and time-travel and worry if they’re wearing uncool trainers - sadly still seems a challenge for our industry. Adults can be cruel, too.

And we need to do better.

I’d already begun writing Pea’s Book of Holidays when I first heard of hemiplegia, via a chance comment on Twitter. A search took me to HemiHelp, the UK charity for children, young people and families affected by hemiplegia. There I read:

Hemiplegia is a neurological condition that affects children and adults in a similar way to a stroke. It is caused by injury to the brain and it results in a varying degree of weakness and lack of control on one side of the body. It is not just physical mobility that is affected. In fact, most children have additional diagnoses such as epilepsy, visual impairment, speech difficulties, perceptual problems, learning difficulties, emotional and behavioural problems. Childhood hemiplegia is a relatively common condition, affecting up to one child in 1,000.

I thought: that’s a lot of kids for something I’d never heard of. Then I thought: I can do something about that.

That’s when the fear kicked in. The idea for Pea’s Book of Holidays was already set: a funny family outdoorsy Famous-Five-ish adventure, which would gently unpick some of the murkier side of Blyton along the way. Could I take a kid with hemiplegia camping? I was already talking about race and prejudice in my book full of non-traditional families: was this going to make it feel like some sort of diversity training manual instead of a fun mystery with a dog in it?

And then the big questions. Do I have the right? What if I get my representation wrong? Is it safer not to try?

Of course it’s safer not to try. It’s safer not to write anything at all – but then we’d have no books. I asked Hemihelp’s Facebook group for advice, and was overwhelmed by their positive support for the book. Hemihelp put me in touch with two consultants, Joanna Sholem and Rosalyn Burbidge, who shared their own personal and family experiences, and read my embarrassingly underinformed first drafts with a kind but firm editorial eye.

The result?

Ryan Munro is a Scottish ghost-hunter, aged 12. He’s on holiday with his joke-obsessed little bro Troy and Max, their dad; they live with sceptic Mum but this summer it’s Max’s turn. Ryan desperately wants to find a ghost in Corfe Castle to make Max proud - and to prove to those weird girls at the tea rooms that ghosts are definitely real.

Ryan has hemiplegia - which means he wears a splint on his arm and leg, Troy has to help him with some practical tasks, he’s learned to play his Xbox one-handed, he gets tired and snappy, and when he says he wants to prove himself to his Dad he really, really means it. His impairments are part of him and affect every day of his life - but they are not who he is.

Does he represent all young people with hemiplegia? Of course not. He doesn’t represent all Scottish 12-year-olds with divorced parents either. But he’s there, not to learn a lesson or teach one, but to be part of an adventure.

Advice for authors:

• Don’t second-guess yourself out of writing inclusively. Writing is already hard. And here’s this other thing that’s also hard. Why make the effort? If you have no investment in making your fictional world honest, authentic and meaningful to its readership, then... ok. You sound super-fun. But perhaps children’s fiction isn’t for you.
• Do the work. “Nothing about us without us.” A few quick Googles aren’t going to cut it; you need real experiences as well as facts. Ask the stupid questions. Share your work. Listen. Edit.
• Accept that you will fail. However hard you work, and however many well-informed people read over your efforts, your work can’t represent everyone. I sometimes get asked to check a manuscript’s LGBTQ content, as if I can stamp it with an official gay seal of approval. Guaranteed to offend no one! 100% stereotype-free! After all, The Curious Incident of the Dog in the Night-Time is lauded by many as a remarkable insight into life with Asperger’s syndrome; others feel misrepresented by it. If yours is the first time a reader has met a fictional someone “like them”, it’s almost inevitable that you will disappoint.
• Do it anyway. Because we need more of these narratives, not fewer. Not one single story, but many.

Susie Day’s Pea’s Book of Holidays is available from the Guardian bookshop. You can find out more about hemiplegia on the HemiHelp website.