By Laura Smith-Spark, CNN
London - A UK report into allegations of the sexual abuse of children by people in, or close to, government in the 1970s and 1980s has sparked renewed criticism of the behavior of senior British government officials from that era.
The "supplementary report" to an inquiry led by children's charity chief Peter Wanless and senior lawyer Richard Whittam was triggered after new documents relating to the allegations came to light after their original 2014 review had ended.
It comes at a time when Britain has been rocked by revelations involving the sexual abuse of children by public figures -- including UK entertainer Jimmy Savile -- and allegations that the British establishment may have sought to cover up historic abuse claims involving some former senior politicians.
In the latest report, Wanless and Whittam write that issues of crimes against children "were given considerably less serious consideration than would be expected today."
They highlight what they call one striking example, taken from a 1986 letter from Sir Antony Duff, then head of Britain's domestic security service MI5, to the permanent secretary to the Cabinet, Sir Robert Armstrong, following an inquiry into claims a parliamentarian had a "penchant for small boys."
That investigation concluded, write Wanless and Whittam, by accepting the lawmaker's denials, and they quote an observation in the MI5 letter to the government: "At the present stage ... the risks of political embarrassment to the Government is rather greater than the security danger."
Wanless and Whittam continue: "The risk to children is not considered at all."
The letter dates from November 1986 when Prime Minister Margaret Thatcher was in power.
Charity: 'Misplaced priorities'
A spokesman for the charity Wanless heads, the National Society for the Prevention of Cruelty to Children, said the latest report showed "there is a clear sense of the misplaced priorities of those operating at highest levels of government, where people simply weren't thinking about crimes against children and the consequences of those crimes in the way that we would expect them to."
Simon Danczuk, a lawmaker who has been among those leading the campaign for justice for victims of historic cases of child abuse, said the new report showed that "the full weight of the British establishment, including MI5, colluded in a cover-up to protect politicians who sexually abused young boys."
The names that crop up in the newly found papers are those of former Cabinet minister Leon Brittan; Conservative lawmaker Peter Morrison, who was an aide to Thatcher; former minster William van Straubenzee; and Peter Hayman, an ex-diplomat.
The papers also include references to the Kincora Boys' Home in Belfast, Northern Ireland, which has been the subject of numerous sexual abuse claims concerning boys in its care in the 1970s.
The Cabinet Office said the new documents -- which the government published Wednesday -- had been discovered among "assorted and unstructured papers" largely uncataloged. It apologized for the delayed release.
The 2014 review by Wanless and Whittam sought to find out what the Home Office knew, and what it did, about abuse allegations between 1979 and 1999.
Wanless and Whittam said the additional material -- which they saw for the first time this year -- didn't change their conclusions.
The 2014 review said that while it was "very difficult to prove anything definitive" when looking at imperfect paper records from 30 years ago, it had "not uncovered any evidence of organised attempts by the Home Office to conceal child abuse."
'Only the tip of the iceberg'
Besides the historical claims, recent abuse scandals in Rotherham, Oxford and the Greater Manchester area have revealed serious failures by police and local authorities to safeguard vulnerable children from sexual exploitation.
Amid continuing public concern, an independent inquiry opened this month with the aim of reviewing "the extent to which institutions in England and Wales have discharged their duty of care to protect children against sexual abuse."
"Public concern about institutional failure to protect children from sexual abuse has mounted with the growing realisation of the sheer scale of this problem," said Lowell Goddard, the senior New Zealand judge appointed to head the inquiry.
UK Home Secretary Theresa May told Parliament in February that what had been uncovered so far on the issue of child sex abuse "is only the tip of the iceberg" and that more must be done to expose "hard truths" and bring perpetrators to justice.
"With every passing day and every new revelation, it is clear that the sexual abuse of children has taken place and is still taking place on a scale that we still cannot fully comprehend," she said.
"What we do know is that the authorities have in many different ways let down too many children and adult survivors."
CNN's Andrew Carey and Hannah Calder contributed to this report.