When deaf children are abused, they can have extra difficulties in letting people know what has happened. One incidence of abuse from an east London school for deaf children has demonstrated the problem in a See Hear and Newsnight investigation which has named the perpetrator for the first time.
With limited vocabulary and lack of awareness, many children at Woodford School for Deaf Children tried to tell people they were being sexually abused by the husband of the headmistress, without success.
"There was a busy road with a playground and there'd be people walking past but we had no communication because we couldn't speak, we couldn't sign and they couldn't understand our voices," says James, not his real name, a pupil at the school in the early 1960s. "We'd try and write notes but our vocabulary was limited. The only word we knew was 'rude'."
It is difficult for a child to tell an adult that they have been touched inappropriately, sexually assaulted or raped. If that child is deaf and can't speak well, or if they use sign language, then communicating even the simplest things can be a challenge.
"We'd make paper aeroplanes and throw them. People would pick them up, laugh and wave and go on their way and we would feel frustrated," says James.
About 90% of deaf children are born into hearing families where the household doesn't use British Sign Language. If the families don't go on to learn BSL, this can create a linguistic barrier. This can have a negative impact on their education and knowledge as witnessed by families over the years and with some research to back this up.
Until recently, most special education took place at residential schools, where deaf children would board on a weekly or termly basis.
In 1951, Eric and Beatrice Ingall set up the Woodford School, a private school for deaf children in east London. Beatrice was headmistress and Eric the bursar, driver and handyman. The couple lived in the same boarding house as the pupils.
The school taught by the "oral" method where they used speech in all lessons. It works by encouraging children to speak and lip-read English, rather than use sign language. It was common to teach deaf children with this method at the time, and is still used today.
If any pupils at Woodford were caught signing to each other they were punished, typically with a ruler on the hand, or by taping pupils hands behind their backs. Few deaf schools taught sign language then.
One former pupil recalls having to stand outside a classroom with the sign "I am a goldfish" around his neck after failing to talk properly. Many former pupils report they were made to feel ashamed for being deaf. They were forced to call the couple Daddy and Mummy, or face punishment. This shame and sexual abuse continued at the school across three decades.
Some pupils have remained silent about their ordeal for many years and the perpetrator of the abuse is named for the first time by BBC's See Hear and Newsnight.
"It was something that took place every day, at any time, morning, afternoon, evening, round the clock. And I didn't see my family from when I was 4 until 11," says former pupil "Miriam" - not her real name. "I was a prisoner in that school."
One victim, Sandra, says: "He smiled at me when he was doing it. I never smiled back. I just sat there terrified. What was I supposed to do? He abused me nearly every week for two years. When he left the bedroom I cried. I refused to cry in front of him because it would be more pleasurable for him. He enjoyed seeing me suffer and I didn't want him to see me like that."
Another pupil, David, says: "I didn't know anything. I thought it was supposed to be fun and that it was acceptable. I didn't realise so I didn't try to stop him. I thought it was a part of normal life."
In 1964 a case was taken against Ingall at the local magistrate's court. He pleaded guilty to indecently assaulting two pupils and, even though he asked for seven other offences to be taken into consideration, was fined only £50 and prohibited from being in the school for two years. It's thought that the couple's influence and connections with the local establishment, some of whom gave good character references at the trial, led to him getting off lightly. A former mayor of Woodford had testified in his favour, suggesting that overwork might have caused the "lapse".
Whilst Ingall was the main abuser, Mrs Ingall is accused of turning a blind eye to what was happening. Despite the convictions, she allowed her husband inside the school to look for his next victims.
"Ingall's wife came and she saw," says Miriam, "...she completely wasn't bothered and left me there with him and went back to her bedroom."
It takes, on average, seven-and-a-half years for a sexually abused child to finally disclose to anyone what has happened to them and, for many, disclosure does not take place until well into adulthood, according to recent research by the NSPCC.
David, abused from the age of three, says it wasn't until he became an adult and attended a course on protecting children that he realised what had happened to him.
Some described their wish to escape and how they would plot to achieve it. Sandra told of how she felt envious of a fellow pupil who was being carried out of the school in an ambulance, being unconscious after a fall. Another pupil, James, recalled a time when he stole a ring, deliberately wearing it in public in the hope that the police would come to arrest him and take him away.
It is said by the victims that Ingall often visited the classrooms to take his pick of the children. When he came in, every child was terrified that it was going to be their turn that day.
He continued his abuse throughout the probation period, and into the next decade. Mrs Ingall retired as headmistress in 1984 and the school itself closed in 1991.
In 1992, nearly 30 years after the original conviction, another complaint was made but the police did not investigate it because Ingall was believed to be senile.
Despite this, seven years later a group of ex pupils rallied together to make fresh charges against Ingall and others. With Ann Stuart, a child abuse police investigator for the Metropolitan Police, they worked on this case for nearly five years and were disappointed when the case was discontinued in 2004 on its second day.
Judge Michael Burr cited the reasons that Ingall was too old, that other potential witnesses had died and that the survivors had left it too long. The remaining witnesses, however, did receive CICA compensation from the Home Office as victims of crime.
Beatrice Ingall died in 2007 and Eric Ingall died in 2012. Their deaths brought little comfort to those that were abused.
This investigation is a collaboration between Newsnight and See Hear, the BBC's long-running programme for deaf people. Watch the report on Newsnight, BBC Two at 22:30 on 4 November 2015. Or catch up on BBC iPlayer afterwards.
Resources to teach deaf children about the dangers of child sexual abuse can be found on the NSPCC's website.