Jim Gamble of the City and Hackney Safeguarding Children Board (CHSCB) - who uncovered the huge lapse in a Serious Case Review - blasted the Met for failing to act upon the initial tip-off

A foster father accused of hoarding child porn was free to rape orphans in his care for 14 years after police failed to follow-up a tip-off claiming he was showing kids pictures of children being abused.

The anonymous phone call to a London police station in 1999 - detailing the nature of the man's supposed offences - was not acted upon.

In the years that followed, the twisted pervert committed 20 acts of child abuse - including rape, sexual assaults and acts of indecency - against five schoolgirls he and his wife had offered to care for under Hackney Council's foster scheme.

The man was jailed in 2013, with prosecutors fearing the attacks carried out between 1999 and 2008 were filmed and uploaded online for others to view.

However, local child protection agencies are furious after uncovering the failure of police to investigate the initial allegations made against the man, said to have occurred before his first documented case of abuse.

Jim Gamble of the City and Hackney Safeguarding Children Board (CHSCB) - who uncovered the huge lapse in a Serious Case Review - blasted the force.

He said: 'The police failed to deal with an early anonymous complaint about the main offender's use of indecent images. I am convinced that had they done so the vast majority of the offending (known to us) could have been prevented.

'Police knew an allegation had been made against a foster carer and on each of the occasions when he was subject to the regular checks that carers are required to undergo, a decision was made not to share that information. In my opinion this case provides evidence that this system needs to be urgently reviewed.

'Whilst this opportunity to intervene occurred over a decade ago, I welcome the fact that the police have accepted the recommendation to investigate this incident and I am reassured by the steps they have taken to restructure and realign responsibility and oversight for contemporary investigations.'

The CHSCB confirmed that Hackney Council had not at any point been made aware of the allegations against the man - despite officers carrying out no less than four background checks on him as he and his wife took in 30 children.

Mr Gamble added that had they been, children would have immediately have been stopped from being given into his care.

The anonymous phone call to a London police station in 1999 - detailing the nature of the man's supposed offences - was not acted upon. In the years that followed, the unidentified man and his wife took more than 30 children into their home. Five schoolgirls were then sexually abused (stock photograph)

Peter Saunders of the National Association of People Abused in Childhood branded the police oversight as being among the worst he has ever encountered.

He said: 'Foster children are extremely vulnerable. That's why foster parents, the majority of whom do a brilliant job, should be doubly investigated if there's a hint of suspicion.'