Laws compelling people in positions of trust to report child sexual abuse and a national compensation scheme for victims should be introduced, a seven-year inquiry into institutional failings in England and Wales concluded.

The Independent Inquiry into Child Sexual Abuse (IICSA) described the sexual abuse of children as an “epidemic that leaves tens of thousands of victims in its poisonous wake”, as its final report was published on Thursday.

But the inquiry’s chairwoman said it was “unfortunate” the Prime Minister’s resignation on the same day may take attention away from the work.

Among a raft of wide-ranging recommendations, IICSA called for a “national redress scheme” to get compensation for victims “let down by the state and non-state institutions in the past” to be launched.

The UK Government should create a post for a minister for children at cabinet level and the Welsh Government should make sure there is cabinet-level responsibility for children while a Child Protection Authority (CPA) should also be established to “secure a much stronger focus on the complex work of child protection in the relevant institutions and statutory agencies”, the 458-page document said.

The £186.6 million inquiry, set up in 2015, looked at 15 areas scrutinising institutional responses to child sexual abuse – including investigations into abuse in Westminster and the church – and more than 7,000 victims took part. But it had to survive a number of early blows with resignations and blunders initially throwing the future of the inquiry into doubt.

Some 325 days of public hearings saw testimony from 725 witnesses – including three former prime ministers, an ex-director general of MI5, victims, senior police officers and church leaders – while 2.5 million pages of evidence were processed and scores of reports published with 87 recommendations already made as a result.

Six previous recommendations put forward by the inquiry were reissued in the final report as they had not been “properly addressed or acted upon by those to whom they were directed”.

A further 14 proposals were set out in the overall findings on Thursday and IICSA said it expects the UK and Welsh governments, and other institutions mentioned, to act on these “promptly” and report back on the steps they have taken within six months of the final report’s publication.

Scathing findings from the inquiry, published in 2019, on the investigation into abuse allegations at the Church of England concluded the King, who was then the Prince of Wales, was “misguided” in his support for shamed clergyman Peter Ball who was cautioned for gross indecency in 1992.

Professor Alexis Jay, chairwoman of the inquiry, said: “For too long, child sexual abuse has been considered a problem of the past, despite lifelong impacts on its young victims.

“Its extent cannot be underestimated; the sexual abuse of children is an epidemic that leaves tens of thousands of victims in its poisonous wake and some will never recover.

“Across our investigations … we heard time and time again how allegations of abuse were ignored, victims were blamed and institutions prioritised their reputations over the protection of children.

“The nature and scale of the abuse we encountered were horrifying and deeply disturbing. As a society, we simply cannot file it away and consider it a historical aberration when so much of what we learned suggests it is an ever-growing problem, exacerbated by the current and future threat of the internet.

“I urge the UK government, the Welsh Government and all other relevant institutions to implement the inquiry’s recommendations as a matter of urgency.

“Unless we are prepared to accept a world where our children, and their children, are always in danger of becoming victims of this terrible crime, action must be taken immediately.”

When asked about the implications of the Prime Minister’s resignation on the findings, Prof Jay later told the PA news agency: “Perhaps from a rather selfish perspective it’s unfortunate that it may perhaps take attention away from this hugely important report.”

Facing questions over how likely it was the changes recommended will be adopted, Prof Jay told a press conference: “We don’t have the power to force the government to do it, but they should do it and need to do it.”

The inquiry has not estimated how much it will cost to implement the recommendations.

The Online Safety Bill had “already taken too long to be enacted” and “must be urgently progressed,” adding that until the “worldwide phenomenon” of trading and distributing indecent images of children on the internet is tackled by the industry, “children will continue to be harmed”, Prof Jay added.

NSPCC chief executive Sir Peter Wanless said: “This must be a defining moment for child protection. We now need political leadership to turn this inquiry into lasting change.”

There are 3.1 million victims of child sexual abuse in England and Wales, according to the 2019 Office for National Statistics crime survey, accounting for 7.5% of the population aged between 18 and 75.

In 2020/21 there were an estimated 500,000 victims of child sexual abuse, according to the Centre of Expertise on Child Sexual Abuse.

According to the findings, it is estimated in any year group of 200 children, 10 boys and more than 30 girls will experience sexual abuse before the age of 16 – a fifth of the total.

The latest statistics suggest the age at which children become victims is getting younger, with sexual abuse offences recorded by police where the child was under the age of four rising by 45% in recent years. On average, victims only disclose their abuse after 26 years, IICSA said.

Former prime minister Theresa May, who set up the inquiry when she was home secretary, said: “Thanks to the painstaking work (of the inquiry) … we now know the true scale of the abuse our children have suffered over many decades.

“We can no longer hide from this as a society.”

In his first full day in the job, Home Secretary Grant Shapps said his department would act on the report, saying “there is much more to do”.

The Government will respond within six months, when all of the recommendations have been considered, the Home Office said.

Mr Shapps praised the victims who came forward as part of the inquiry and said their “bravery will not be forgotten”, adding: “I will keep their voices front and centre in everything I do and I will ensure that the findings of the inquiry, and their invaluable testimonies, are acted upon.

“To date, we have already taken action to tackle this abhorrent crime and learn from the lessons of the past, but I know there is much more to do. This is the start of a new chapter in our efforts to put an end to this terrible crime.

“I want to give assurances – where we can act quicker, we will.”