"The sickening moment I discovered my kids' babysitter was a convicted paedophile."

A UK mother has detailed the horrifying moment she learned a convicted paedophile was babysitting her children.

Ray Dell, 49, had previously been jailed for four years for seven assaults on a child and possessing indecent images of children.

Upon his released, he befriended two local Hull mothers and began to babysit their children.

The mother – who did not want to be named – told Hull Daily Mail she first met Dell at the house of another mum whose children he cared for.

She said she knew him for "a long time" before she left him alone with her children.

She told Hull Daily Mail she was alerted to Dell's history via a phone call from social services.

"They'd caught him searching for indecent, Grade A, images over the internet. They looked at his computer and found a very close up image of my daughter he'd made from a family photo," she said.

She confronted Dell about the allegations.

"He admitted he had sexual thoughts. He said, 'I didn't touch her'. He is just disgusting. I felt physically sick," she said.

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"He admitted it to me over the phone. I felt overwhelming guilt."

The woman said Dell admitted he had used her and another family to "challenge" himself to be around children.

"He told me he had used us as a challenge to be restrained. I felt sick. I think people like that are just biding their time," she said.

"He came across as so genuine. From the first time I met him it was like I'd known him for years. But that's it, paedophiles don't have the label stamped across their forehead. They work their way into families to get their trust.

"He helped build a swing in the back garden, he helped around the house. He seemed really genuine and I didn't suspect anything."

Dell was sentenced to 18 months in prison for breaching a sexual offences prevention order. He was also sentenced to a further six months for taking an indecent photograph of the child.

The girl's mother said she has struggled with trusting anyone to look after her children in the wake of the incident.

"I didn't want to leave my kids with anyone afterwards. I didn't take them to school, I just felt like I couldn't trust anyone," she said.

"I still don't let people come to my home."

The woman is now calling for the names and photographs of convicted paedophiles to be made public in the UK so other parents don't find themselves in a similar situation.

"I'm disgusted he was able to get into my house without any warning of his past," she said.

"People need to be made aware of names, and the cities or counties they live in. Someone with these convictions should not be able to do this. People should know about them. They should get longer sentences and not be able to hide them."