"I CAN only describe it as a living hell."

The despair in Mark Bambrough's voice is clear, as he describes trying to cope with a daughter who has what is known as a phobia of speaking.

Despite living in the same house as her parents, the 19-year-old doesn't speak to either of them. She has struggled with selective mutism (SM) since childhood, leading to depression and obsessive compulsive disorder (OCD).

According to NHS guidance, SM is an anxiety disorder that prevents children speaking in certain social situations, such as school lessons or in public. Often they speak freely to family and friends at home. While the term 'selective mutism' implies choice, the guidelines say SM isn't about voluntarily refusing to speak, but being unable to speak, feeling frozen, in situations that provoke it.

It affects one in 150 children, usually starting at primary school age. Often they have other fears or social anxieties and may have additional speech or language difficulties. If left untreated, it can continue into adulthood.

Mark became aware of his daughter's condition when she became unusually quiet at her Great Horton primary school. "She was okay at home but we noticed a change in her last year," he says. "She wasn't mixing and was anxious."

When she moved up to secondary school, the anxiety became too much for Mark's daughter and she was home schooled.

"When children with SM reach 13 or 14 the normal anxieties of adolescence are magnified; they don't want to draw attention to themselves and become compliant, giving closed answers. This is often mistaken for shyness or rudeness," he says.

It was watching television documentary My Child Won't Speak, about three children with SM, in 2010 that Mark to learn more about the condition. Now he's trying to raise awareness and help schools spot the signs.

"It is the most misunderstood and misdiagnosed of all mental health issues, and if not detected the onset can be transitory and lifelong," says Mark. "It's a complex condition but relatively easy to treat, if caught early enough. It occurs out of the home in the early years, usually when a child starts school, and if it's not picked up on they learn to become silent. By the time they've got to 11 or 12 it can be too late. If left untreated, it will trawl other attachments such as OCD and depression. This is where my daughter is now, and we're still trying to get the appropriate service for her.

"Her OCD is so controlling she can't take her medication. It can take her hours to eat a meal. We need to get her into a respite situation to try and break the OCD, but we can't make her have therapy.

"In the last couple of years she has become very silent with us. We feel like our lives are on hold."

Mark's daughter was referred to the Child and Adolescent Mental Health Service, but he says there is limited understanding of SM.

"Hundreds of thousands of pounds has been spent on her through the NHS. If this had been sorted at primary school level it would've cost just a couple of hundred pounds in training," he says."Why isn't there a service for SM when the prevalence rates are the same as other disorders like ADHD, Tourette's and autism?

"I'd like the term 'selective mutism' to be changed to 'situational mutism' or 'situational anxiety'. It is failure to speak, rather than choosing not to speak."

Mark says his daughter was born with a "predisposition of anxiety" and he can trace signs of SM in his own childhood.

"My trigger was being rapped on the head by a teacher, I was about eight. I developed a fear of teachers and anyone in uniform. That was in 1964 and we've not come that far since. I was lucky that I loved sport and music, so I had outlets," he says.

Mark carried out his own research into the condition, contacting 100 primary and 44 secondary schools in the Bradford district. "The number of cases of SM or suspected SM is up to four in every primary school," he says. "I think it's mainly down to two reasons - the abolition of middle schools, causing an often traumatic transition from primary to upper school, and the learning of a second language. SM prevalence rates increase among ethnic minorities where English isn't spoken at home."

Mark, who left his job to care for his daughter, is a a volunteer for iSpeak.org.uk, a website supporting teenagers and young adults affected by SM and their families. He is running an awareness-raising campaign, and is planning a fundraising event in Bradford for next April. He has also contributed to In Our Words, a collection of stories from people living with SM.

"We're aiming to bring structured training to primary schools so children are risk can be identified before they're fed into upper schools," he says. "Something needs to be done at Parliamentary level too. Long term, we're looking towards treatment centres like they have in America."

* For more about selective mutism go to ispeak.org.uk