A paedophile jailed this week for sexually abusing three young boys worked with vulnerable children in Westminster for six years after police background checks failed to flag up a caution for spanking children.

Edward Wright, 52, received a caution for indecently assaulting children aged 12 and 16 by spanking them in 1993, but the incident was not reported in a police Criminal Records Bureau (CRB) check.

It should have seen him immediately rejected by Westminster’s Youth Service, but the CRB check came back clear and he was able to work with children aged as young as seven until his arrest last year.

The Metropolitan Police blamed “human error” for failing to spot Wright’s caution.

A spokeswoman said: “Though the record of the caution was located during the vetting process, it was not passed to the disclosure team for further consideration.”

On Tuesday, Wright was jailed for six-and-a-half years for repeatedly molesting three young boys between 1986 and 1994.

All three of his victims, including two brothers, went on to become drink and drug abusers, while one of them is now serving a life sentence for murder, the Old Bailey heard.

Wright, of Streatham, was found guilty of three counts of buggery, having already admitted possessing a “large number” of pornographic images of children.

There are no formal allegations of child abuse during Wright’s time working for Westminster between 2005 and 2011. However, the council confirmed he was officially cautioned for inappropriate behaviour after he offered a child a lift outside of work hours.

One of Wright’s former colleagues at Westminster said he feared other children may have been abused.

“My worst fear is that he has done things to young people that we knew and Westminster allowed it to happen,” he said. “We raised concerns about his inappropriate behaviour but they were swept under the carpet. A lot of us didn’t trust him around young people but he was still able to take children on trips away.”

Westminster’s director of family services, James Thomas, said the council acted promptly to suspend Wright in February 2011 and was “deeply shocked to learn of the allegations against him”. He said “no Westminster young person has been identified as a victim” but the council continues to work closely with police.

A police spokeswoman confirmed “refresher training” had been introduced for staff.

Det Insp Justin Armstrong said: “It is possible he may have committed further crimes.” He said anyone who believes they may have been abused should call police on 020 7230 3314.