A convicted sex offender being monitored by police was free to flout a ban on meeting children and chatted up youngsters at church services.

David Cox had been given a sexual offences prevention order (Sopo) banning him from unsupervised contact with children, which was being enforced by Thames Valley Police.

Yet the Oxford Mail can reveal that over a two-year period he was able to freely attend Sunday services at St Ebbe’s Church, Oxford, where he was seen talking to children, including a vulnerable underage girl.

According to information given to the court, this was not discovered until Cox was caught downloading extreme pornography by a support worker at the Lucy Faithfull House hostel.

Last night Thames Valley Police defended their handling of Cox, which amounted to “officers regularly meeting Cox and reviewing his situation to manage the risk he posed to society”.

However, a children’s safety campaigner, Enough Abuse founder Marilyn Hawes, said she was horrified police had not monitored the 54-year-old and discovered he was meeting children.

Cox, of Speedwell Street, was jailed for two years at Oxford Crown Court on Thursday having admitted breaching a Sopo between January 1 and July 31.

He also admitted five counts of possessing extreme pornography and one charge of making indecent photographs of children.

His attendance at St Ebbe’s, including going to Sunday family services, bible study lessons for the homeless and taking piano lessons from a member of staff, did raise suspicions with parents and clergy.

Judge Mary Jane Mowat said: “The case was opened on the basis of frequenting this church, a children’s service, and really hanging around, in quite an obvious way, in particular one girl who was quite vulnerable.”

Peter Du Feu, defending, said: “One of the girls (at church) in particular was vulnerable and he seems to have been attending church when services would involve children.

“Clearly it’s a breach, but it doesn’t seem to have been taken further than him wanting to be in the company of children.

“I suppose ‘chatting them up’ as the Crown might put it.

“At 54, he has long-term problems that aren’t going to be solved.

“He represents a management difficulty wherever he is.”

A police spokesman said: “Thames Valley Police was responsible for managing him as part of a sexual offences prevention order.

“As soon as it came to light that Cox was breaching his order, officers immediately intervened and he was arrested.

“Off the back of that arrest, further offences have come to light for which he has now been convicted.

“Although it is never possible to entirely eliminate risk, Thames Valley Police has a good record for the management of these offenders.”

But Mrs Hawes said it revealed the management of sex offenders was flawed. She believed Thames Valley Probation Service, part of the Multi-Agency Public Protection Arrangements scheme dealing with such cases, should be involved in proactive monitoring.

Mrs Hawes added: “If Thames Valley Police are happy with what they have allowed to happen, then they should be ashamed.”

The Rev Peter Wilkinson, of St Ebbe’s Church, said it took the protection of children “enormously seriously” and it had raised its concerns with police in July last year.

Cox was given a lifetime Sopo and must sign the sex offender register for 10 years.

Sex criminal figures Most recent figures show there are 282 sex offenders living in Oxfordshire.

This is a rise from the 2010 Mappa figures, published by the Ministry of Justice, which showed 251 living in the county.

The figures, which were released in November, record the number of convicted sex offenders in the county on March 31.

At present, 0.043 per cent of Oxfordshire’s population of 648,700 people are sex offenders.

The latest annual Mappa report’s introduction said its contents sent “a clear and consistent message to the public that there are a number of measures in place to increase protection and offer reassurance that we are doing all we can to prevent offenders from reoffending”.