A school caretaker has been jailed for having sex with an underage pupil and making calls to chat lines from an office phone.

Adam Riley's victim, who was 15 at the time, yesterday said she was “so relieved” the 27-year-old, who police consider a “high risk” to other children, has been locked away for five and a half years.

She said: “I am very relieved justice has been done. This is the end of my ordeal with him.”

Riley, who was given accommodation within the grounds of St Paul's Catholic College in Burgess Hill where he worked, admitted having sex with the girl while she was studying there.

His sentencing at Lewes Crown Court came a year after his twin brother Ian was convicted of filming young boys in changing rooms at another school where he worked as a karate teacher.

Riley, of Colwell Road, Haywards Heath, also admitted accessing school records to find the girl's phone number, groping a woman and making dozens of night time calls to sex lines from a school phone.

In one conversation with a sex worker he asked her if she wanted to watch him have sex with a four-year-old child.

The chatline worker was so horrified she called police, starting the investigation that led to Riley's arrest in August 2009.

Riley, a former pupil at the school, was offered work as a caretaker soon after he left the college.

In court he admitted having sex with the 15-year-old but said she lied to him about her age.

But his signature in a school yearbook proved he knew she was underage.

Prosecutor Richard Barton said: “He would have known full well what year she was in. There was evidence that he sought out her details from the school files.”

Riley also admitted he groped one woman and exposed himself to another.

He showed no emotion as he was sentenced by Judge Charles Kemp and told he would now be on the sex offenders register for life.

Speaking outside court Detective Inspector Ali Eaton said: “His victims went through the horror of reliving sexual abuse in the court room so this man could be locked away.

“Having to come face to face with him again is no small feat but without them we can't put away predatory sexual offenders like Adam Riley.”