Clive Driscoll, who rose to the rank of chief inspector before retiring, said he might as well have been phoning "from the moon" when he made the call in 2001 about the scout John Butcher.
Butcher was convicted in 1993 of attempting to smuggle child-abuse images into England from the Netherlands and in 2009 he was put on the sex offenders register for seven years after he was caught looking at indecent images.
Butcher, 67, is adamant he has "never physically abused children".
The revelations -- which will add to the deepening dismay of how football reacted to the allegations at the time in a scandal that has rocked the foundations of the multi-billion pound sport -- come days after London police revealed they were looking into allegations of abuse at 30 London clubs including four unnamed Premier League sides.
It was after Butcher's earlier offence that Driscoll got in touch with Chelsea, Crystal Palace and Millwall over Butcher, who operated as a freelance scout.
"I spoke to Millwall, Chelsea and Palace about Butcher and warned them about him in 2001," he said.
"I was a detective inspector at the time and I was phoning them from the police, but I might as well have been phoning from the moon.
"I was saying he had a conviction but they just treated it as a football matter."
Driscoll, who successfully brought the killers of black teenager Stephen Lawrence to trial after years of frustration over the initial investigation on the part of the victim's family, said he impressed on the clubs the seriousness of the matter.
"All they were concerned about was that he was a good scout, the football -- I was saying this is slightly more important than that, that this guy had a conviction for importing child pornography."
His revelations will make further uncomfortable reading for Chelsea -- whose present owner, the Russian oligarch Roman Abramovich, took over two years after Driscoll informed the club of Butcher's conviction.
His regime was lambasted for imposing a gagging order on former youth player Gary Johnson as a condition of a 2015 agreement to pay him 50,000 pounds ($63,850, 59,230 euros) over abuse he suffered at the hands of former scout Eddie Heath.
Several other former Chelsea youth players -- including a retired policeman -- have come forward since Johnson broke the gagging order to allege Heath, who died in 1983 aged 54, had either abused them or they knew of his abuse.
Chelsea have launched an investigation -- headed by a lawyer -- into the allegations about Heath with some speculating that the club could face a group action law suit costing them potentially millions.
Heath was sacked by Chelsea in 1979 by then manager Geoff Hurst, not for sexual impropriety but because he spent more time decorating his office than scouting.
He moved on to another London club, Charlton Athletic, where a former youth player alleges he was abused by him.
Johnson told the BBC he is going to seek greater compensation for the abuse as it had "taken away my childhood".
Palace too have been severely criticised for their attitude to Driscoll's phone call in a report published on sex abuse at childrens' care homes in south London by a support group called the Shirley Oaks Survivors Association.
"When former Met (London Police) Officer Clive Driscoll approached Crystal Palace with regard to concerns about Butcher they were dismissive and derisory," read the report.
"We now know that numerous children were taken from Shirley Oaks to Crystal Palace for special treats, sanctioned by the management."
Palace said they were looking into the allegations but added that, as far as they knew, Butcher never had a formal role at the club.