Colin Waterfield has been jailed for 21 years for a string of sexual offences
The vile pervert was jailed after he was found guilty last month of rape and sex assaults involving eight children and one adult and possessing extreme porn.
Waterfield had denied all the offences, which happened between 1973 and 1995.
But the jury took less than five hours to convict him of 24 of the 30 counts he faced following his sinister 22-year reign of sexual terror.
The 70-year-old denied all the offences which were carried out between 1973 and 1995
Waterfield, of Norwich, was at last behind bars after police opened a new investigation into his shocking catalogue of sex crimes in 2013.
Detectives originally launched a probe into allegations that he was a serial sex attacker in 1994 after five traumatised child victims alerted police.
Officers put together a file for the Crown Prosecution Service (CPS).
But CPS officials stunned his distraught victims by opting not to charge Waterfield.
The system let those children down because no prosecution followed
Judge Stephen Holt
They insisted there was not enough evidence to convict him in court.
A CPS East of England spokesman said: "It was decided at the time and after a thorough review of all available evidence that there was not a realistic prospect of conviction."
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Police received new complaints from Waterfield's victims in 2005 but didn't act because they claimed they had no new evidence proving his guilt.
Waterfield's case was reopened in 2013 after on of his victims contacted the police
Det Insp Paul Brown, of Norfolk Police, admitted last night that the voracious predator's devastated victims had been "let down".
He said: "We know the police service has not always approached these crimes with the appropriate resources and understanding and as a result victims of sexual offence have been let down.
"A huge amount of work has been done within the police service to improve our response to reports of historic sexual abuse and change the way we investigate these offences."
Det Insp Brown added: "The case of Waterfield has been a complex enquiry over a period of three years.
"I hope this demonstrates to his victims, and people who have suffered at the hands of others, that we are committed to bringing offenders to justice and will give enquiries the resource and time they require."
Det Insp Brown hailed the 21-year prison sentence handed to Waterfield as "really significant".
He said it reflected the "many years of serious sexual abuse of children undertaken by Waterfield".
Judge Stephen Holt told Norwich Crown Court: "One of the tragedies of this case was that five youngsters went to police in the 1990s and interviews were taken and recorded.
"But the system let those children down because no prosecution followed." Judge Holt said the officer in the case pursued enquiries with "diligence and dedication" and that he did not blame the CPS.
Judge Stephen Holt admitted that the system had let down Waterfield's victims
But he stressed that attitudes towards sexual abuse against children were "very different" back then.
Judge Holt said sick Waterfield was "extremely good" at grooming children and had "preyed on numerous youngsters".
He urged the paedophile pensioner to read victim statements in the case which were "desperately sad" and showed many were still "bearing the scars" of the abuse they suffered.
Lori Tucker, defending, said although Waterfield was still denying "most, if not all" of the allegations against him he had started to accept the jury's verdicts. In impact statements read out at court, several of his victims said his sickening abuse had "destroyed" their lives and left many suffering life-long anxiety and depression.
Norfolk Police Child Abuse Investigation Unit (CAIU) reopened the case in 2013 after police were contacted by one of Waterfield's victims.
Officers soon began to unravel a horrific catalogue of abuse dating back decades and involving many victims – many of whom had been vulnerable children at the time.
Waterfield carried out his depraved offences at three separate homes in Norwich.
In September 2014, on the back of intelligence gathered, specialist police teams carried out a four-day search of a house in Costessey, Norwich, and seized a stack of items.
Police also scoured Waterfield's home in the city as they gathered enough crucial evidence to finally stop him.