Jeremy Corbyn was approached in the 1980's by a social worker in Islington, who raised the issue of sexual abuse of Islington children in residential care establishments. I've read several interviews in which she states he listened but took no action. She also says she approached him on a number of occasions at e.g. Stop the War demonstrations, to raise the issue again with no effective response.
The sexual abuse of children, whether by individuals or organised groups has been part of society for as long as we have records or knowledge.
Anyone who has worked in health, police, social work, probation, education or any other organisation coming into contact with children and young people will confirm it's far more common than most would like to accept.
That's the real issue isn't it. Why so many people, often men, are sexually attracted to infants and children. Why some men see children age 11 upwards as fair game because those children are neglected or acting out and preventing parents keeping them safe.