Postman in catalogue of child sex offences
He admitted three counts of grooming, eight counts of sexual activity with a child aged between 13 and 15, nine counts of causing or inciting a child aged between 13 and 15 to engage in sexual activity, four counts of causing or inciting a child under 13 to engage in sexual activity and one count of voyeurism.
He also admitted two counts of making and possessing indecent images.
The former match secretary of Falmouth Town amateur football club also asked for some 460 similar offences to be taken into consideration.
Between 2005 and 2009 Williams pursued hundreds of schoolchildren, signing up to sites such as Facebook and Bebo, posting as a youngster.
He then carefully groomed his victims online, winning their confidence and often asking them to use an Internet video camera, or webcam.
Det Insp Simon Snell said after the guilty plea: "He created a number of spurious profiles, portraying himself as a child and was making contact with children of the same age.
"He sent them questionnaires, asked about where they lived, asking for their mobile numbers, and if they had had sex. He is a manipulative and predatory paedophile."
Williams, who had also worked as a taxi driver, used all of his
positions to bring himself in contact with the children, Det Insp Snell added.
Williams has been remanded in custody for psychiatric reports and will be sentenced on a date to be fixed.
Speaking outside court, Det Insp Snell added: "I hope he now
understands the harm that he has caused."