Call handler on 31yrs at

Retired deputy head Colin, 70, still volunteers every week and recalled: “I said what I now say to all of the children: ‘Goodbye for now – and look after yourself’. I never like to say goodbye, in case they want to call again.

“The man sounded like a devil but I don’t know whether he was prosecuted. That first call made me realise how worthwhile a thing we were doing.”

Dame Esther Rantzen launched Childline on October 30, 1986, which merged with the NSPCC in 2006. Now the Sunday People is teaming up with the charity for its Light Up Christmas f or Children Campaign to raise an extra £ 500,000 a year to train counsellors.

For £4, you can help ensure a counsellor is able to answer a child in need and £20 could fund an entire counselling session for a desperate young person. A quarter of youngsters, 175,000 a year, fail to get through to Childline. And Esther, 77, said: “What if the child who can’t get through is a suicide call?”

Last year Childline counsellors spoke to 22,000 suicidal youngsters. In 31 years Colin, of Malvern, Worcs, has taken 15,000 calls and remembers a teenage girl about ten years ago who, after 20 minutes, calmly revealed she had taken pills about half an hour earlier.

Colin begged her to tell him where she was and when the girl’s mum returned he had to tell her about the overdose and to call an ambulance.

Colin, who does a weekly shift at Childline’s Birmingham office, said: “As a dad and a grandad, I just don’t understand how anyone could hurt a child.”

The internet and social media mean volunteers face a new problems, including cyber bullying and teenagers being blackmailed into sending naked selfies to strangers. Esther said she is haunted by a call she took from a 10-year-old girl who said her dad and his pals were making indecent images of her and were about to do the same with her six- year-old sister.

Even after so long taking such upsetting calls Colin does not plan to quit. He said: “I know the need is always there. Why would I stop?”