A 10-year-old boy with special needs who complained of bullying was forced by staff to listen to classmates listing the reasons they didn’t like him – and had to write these on a hand-drawn poster that was then stuck on his classroom wall.

In a case that campaigners say highlights the need for specialist teaching resources, Damian Lightoller’s son, who has traits of autism, ADHD and oppositional defiant disorder and is on the special education needs register, was told by his peers he needed to “stop shouting”, “stop annoying us” and “be happy, not sad” if he wanted to have better relationships with them.

The incident, which occurred last year at Allenton Community Primary School in Derby but was only recently discovered by his parents, followed the boy (whom the Observer has chosen not to name) telling the school’s behaviour mentor that he was being bullied. “[My son] approached his behaviour mentor and said he was being bullied and was upset the other children didn’t like him,” Lightoller told the Observer. “So, to try to tackle this, his [behaviour mentor’s] idea was apparently to find out why the other children didn’t like him. So he sat [my son] down, asked the other children why they didn’t like him, and tried to tell [my son] to change those things.

“My son sought help from a teacher, and rather than discipline the other children for bullying, [the mentor] blamed the victim and said ‘well you need to not do this, this, this and this’.”

According to Lightoller, the school’s headteacher, Jon Fordham, described the session to them as “restorative justice”. He questioned “why we’d bothered to raise it and why we even had an issue with it in the first place”, Lightoller said. Gillian Doherty, the founder of SEND (special education needs and disability) Action, which campaigns for children with special needs, said: “No child should be singled out and made to feel unwelcome at school. We’re hearing of many children with SEND experiencing mental health difficulties, developing anxiety about school attendance and being excluded from education.

“It’s vital schools seek early specialist advice on how best to support children with special needs without undermining their self-esteem.”

Funding for special needs education has been squeezed in recent years, with the sector engulfed in crisis. Council overspending on “high needs” education budgets trebled in the three years to 2017/18, with many cutting services or raiding other school budgets – which hits provision for children with special needs and disabilities in mainstream schools.

We had no idea that he was getting reminders every day at school about the things that children dislike about him Damian Lightoller, father

Despite the list having being drawn up in November, the boy’s parents knew nothing until he brought the drawing back from school towards the end of term, two weeks ago. They fear it may have increased the bullying of their son, who had an at times fractious relationship with his classmates. “We’ve had a few more incidents of bullying this year than in the past, so it could have made things worse,” Lightoller said. “Early this year another student threw a bottle at my son’s head. That resulted in him needing to go to A&E to have part of his eyelid glued.”

During the year, the boy mentioned some of the children’s complaints as things he disliked about himself. “We had no idea, obviously, that he was getting reminders every day when he went to school about the things children dislike about him,” said Lightoller. “We had no idea where it was coming from – we just thought it was a child that was having a few issues.”

As soon as they saw the picture, the parents had a meeting with the school’s behaviour mentor, who works with perpetrators and victims of bad behaviour, and with Fordham, who is credited with having turned around the school’s performance since taking over, and with whom they had had a good relationship. But the description of the session as “restorative justice” left them “furious, upset and hurt”, said Lightoller.

He added: “A friend who’s a primary school teacher at another school in Derby said she’s familiar with this activity, and you are supposed to sit the child down and you ask their peers to list positive things about the child, and you try to get the child to focus on those positive things. [Instead they] focused on the negative.”

Fordham did not respond to a request for comment. Transform Trust, which sponsors Allenton school, refused to comment.