A paedophile at the centre of a forthcoming historical abuse inquiry advised the Home Office on changes to the residential child care system.
Peter Righton gave "considerable assistance" as an expert in child care to a government report in 1970.
He had earlier left a teaching job over complaints of child abuse. He later became a member of a pro-paedophile campaign group. Righton died in 2007.
The Home Office said it was "absolutely committed" to stamping out child abuse.
In July, Home Secretary Theresa May announced an overarching inquiry into how public institutions had handled historical claims of child sexual abuse.
This followed a campaign by MPs whose concerns included evidence of a wide paedophile network in documents seized from Righton's home in 1992 after his arrest over child abuse images.
The report to which Righton contributed led to major reforms of 1970s children's homes.
It was authored by a Home Office advisory committee and set out how hundreds of new homes should be brought under local authority control.
So-called community homes replaced approved schools - residential centres for "delinquent" youngsters - and involved the employment of hundreds of social care staff.
The report credited Righton, who at the time was an academic specialising in social work, for "considerable" help in a chapter on the training of residential workers.
A former care professional familiar with the events has told the BBC that Righton travelled extensively carrying out research work during the period he contributed to the project and had been to children's homes "all over the country" including Stoke-on-Trent, Wolverhampton, Rochdale and Preston.
"He [used to] go and interview, in approved schools, individual boys and he certainly went to speak to the heads of homes," the former care worker said.
The retired worker - who asked not to be identified - said that Righton "networked" at children's homes, adding: "He was a very dangerous man because he was put in a position where he could abuse trust."
Righton visited the Bryn Estyn approved school in Wrexham where he met staff and children, according to the care worker's account.
The former worker said that Righton had claimed that he "took boys out" and had also said he used "sexual" language with them.
The source added that the words Righton had exchanged with the boys were "not something that you would have in a healthy conversation with a child".
Bryn Estyn was later at the centre of an abuse scandal in which 140 former residents made allegations that they were abused between 1974 and 1984.
An official report described "appalling" abuse at the home and former housemaster Peter Howarth was jailed for 10 years for sexually abusing boys as young as 12. He died in prison.
The Waterhouse report into abuse at north Wales homes described how local councils were "in a state of turmoil" in the early 1970s owing to the new responsibilities imposed on them by the legislative changes of the time.
Howarth had earlier taught at the same special school in Kent where Peter Righton had faced complaints of child abuse.
By the mid-1970s, Righton had become a founding member of the Paedophile Information Exchange (PIE) which advocated sexual relationships between adults and children.
At the same time he became increasingly influential in the field of residential child care, according to Ian Pace, a lecturer at City University who has researched historical abuse at music schools and the influence of PIE.
He said Righton was "deeply involved with the cult of the classical world that was very important to... the paedophile movement", focusing on stories of "Greek love" between men and young boys.
Mr Pace said "some of Righton's interests" were reflected in the Home Office advisory report.
The section of the report which credited Righton called for residential child care workers to be trained in "the growth of civilisation" and "aesthetic values".
The Home Office declined to comment on the revelations about Peter Righton.
A spokesman referred the BBC to the home secretary's comments to the House of Commons in July when she said the government would address two concerns: "First, that in the 1980s the Home Office failed to act on allegations of child sex abuse.
"Secondly, that public bodies and other important institutions have failed to take seriously their duty of care towards children.
"As I informed the House on 7 July, the whole government take the allegations very seriously. That is why I announced two inquiries last week."
In 1992 Peter Righton was fined £900 for possessing images of child abuse and was cautioned over an earlier assault.