Media playback is unsupported on your device Media caption Barber James Williams has developed a way to cut the hair of children with autism

Sitting in a hairdresser's chair may sound simple, but for a child with autism having a haircut can be painful. One barber has developed a unique technique where he will cut a child's hair during long periods while sitting on the floor, on window sills or even in the car.

This weekend, as part of an autism awareness event, he and 11 other barbers will cut the hair of 60 children with autism.

Four-year-old Mason has autism and is non-verbal. He always found having his haircut traumatic.

His parents were at their wit's end after trying to take him to the hairdressers.

Eventually they read on Facebook about a barber who had successfully cut the hair of another child with autism.

It took four months of hour-long fortnightly visits to James Williams' barber shop in Briton Ferry, Neath Port Talbot, before Mason let him cut the hair around his ears.

"I had to join him lying on my stomach," said Mr Williams. "As a barber it is unnatural to have that experience lying on the floor to cut hair as you are always supposed to stand by your chair doing it. The day that happened we were laughing on the floor doing it.

"Mason was just oblivious to everything, he was watching BBC News 15 seconds on repeat. But that was his day, another day it would have been different. He might not have let me near him on his next visit."

He posted pictures of him cutting Mason's hair in his shop on Facebook and it went viral, with actors Ashton Kutcher and Michael Sheen tweeting about it.

"I had all these families from across the world reaching out saying they went through the struggle," said Mr Williams.

Image copyright Claire Prosser Image caption Seb used to run around the barber's screaming, now he will sit still for his haircut

The 27-year-old now has clients who travel from as far afield as Liverpool and Gloucester and has started a charity called Autism Barbers Assemble to try and raise awareness among other hairdressers of how to approach children with autism when cutting their hair.

But what makes parents want to make a 300 mile round trip for a haircut?

Meleri Thomas, from National Autistic Society Cymru, said: "Autistic children and young people can often find having their hair cut extremely distressing because of sensory challenges associated with the condition.

"This means that when an autistic person is having their hair cut, the feeling of hands running through the hair, or hair landing on the face or body and the noise of the scissors can cause distress."

Mr Williams added: "Some hairdressers refuse to cut the hair of autistic children. That's because they will scream and respond badly, but I'm trying to get the message out there that they shouldn't turn them away.

"They just need to be treated differently.

"One of the biggest arguments I have with other hairdressers is when they make someone with autism sit in a chair to have their hair cut.

Image caption James Williams has become a popular hairdresser with parents of autistic children

"But I'll cut a child's hair anywhere - lying on the floor, sitting on the sofa, sitting on the reception desk, on the windowsill, even in a car. I've learnt to listen to the child as well, if the child wants to go in the car I'll say 'let's go in the car then'.

"I try to pick up on the children's emotions. Any child I can see is getting to the point to having a melt-down I make a decision that is enough and we will try again next time. Or they will have a break and an opportunity to calm down."

For five-year-old Seb, who has severe autism, the sensation of having water on his head was distressing.

What is Autism?

There are around 700,000 people on the autism spectrum in the UK

Autism is a hidden disability - you can't always tell if someone is autistic

The term 'autism' is used to describe different conditions including Asperger syndrome and Pathological Demand Avoidance (PDA)

Information from The National Autistic Society

His grandmother used to be a hairdresser and tried to cut his hair, but it would involve his mum holding him still while he screamed.

Eventually his parents heard about Mr Williams through Mason's parents.

Seb's mother, Claire, said: "Up until then when Seb had his hair cut it was something none of us enjoyed, but that we had to do.

"With Seb it is water on his head, so Jim tells him he has a towel there, and counts down for him. Although Seb still grumbles Jim will joke with him. Now he has his hair cut every four to six weeks, a year ago it was when we could - about every three months.

"To start with he would walk around the salon with James following him cutting it when he could. Now he sits in a chair with his iPad and, for the most part, allows Jim to do it. Seb will still shout at Jim, but he jokes with him in response.

Image copyright Claire Prosser Image caption Claire was left upset by trying to take son Seb to the hairdressers because of 'eye-rolling' from other customers

"He has provided a safe place for parents to go with their autistic children. You can go there without fear if your child is screaming and shouting because it is safe, because in a normal setting it is not socially acceptable if there are other people there."

Autism Barbers Assemble is holding an event on Sunday in which 12 barbers will cut the hair of 60 autistic children in Ystrad Mynach, Caerphilly county. Every child will have an hour-long appointment with all proceeds going to autism charities.

"Appointments with me sold out within an hour," said James. "The others were gone within three days. We are planning on four more events this year - in England, Ireland, Northern Ireland and Scotland.

"I eventually want to build a map on a website of hairdressers where autistic children are actively welcomed so parents know where they can go and not get turned away.

"I want to get barbers and hairdressers to understand autism. I didn't know anyone with autism before my first young client. It changed my whole aspect on the world. I have had parents come in here crying who are so happy to find someone willing to go the extra mile for their kid."