Image copyright IICSA Image caption Inquiry chairwoman, Prof Alexis Jay, led the probe into child abuse in Rotherham

The Independent Inquiry into Child Sexual Abuse (IICSA) in England and Wales is investigating claims against local authorities, religious organisations, the armed forces and public and private institutions - as well as people in the public eye.

But it was dogged with controversy after being announced in July 2014, with chairwomen coming and going and lawyers quitting their posts.

Why was the inquiry set up?

Following the death of BBC presenter Jimmy Savile in 2011, hundreds of people came forward to say he had abused them as children.

The spotlight has also fallen on sexual assaults carried out in schools, children's homes and at NHS sites.

Image copyright PA Image caption Jimmy Savile died in 2011

At the same time, there have been claims of past failures by police and prosecutors to properly investigate allegations.

The inquiry was announced by the then Home Secretary Theresa May to "expose those failures and learn the lessons" from the past.

How does the inquiry work?

When it was announced, the inquiry was expected to take about five years to complete. When finished, it will publish a final report of recommendations.

It has already published an interim report with 18 recommendations - some of which have been acted upon - plus other investigation reports.

The inquiry is divided into public hearings into specific areas of concern, with witnesses giving evidence under oath; research into institutional failures in child protection, and the Truth Project, in which victims share their experiences with the inquiry either in private interviews or written form.

The inquiry will not seek to determine civil or criminal liability of individuals or organisations but may reach "findings of fact" in relation to this.

Allegations of child abuse received by the inquiry will be referred to police and material related to Scotland, Northern Ireland or British Overseas Territories will be passed on to the authorities there.

A separate inquiry looking at the abuse of children in care in Scotland has been set up by the Scottish Government.

Who is carrying out the inquiry?

The inquiry is being led by Prof Alexis Jay, a former director of social services who headed the inquiry into child sexual exploitation in Rotherham.

She is being assisted by a panel of advisers: law professor and human rights expert Malcolm Evans; child protection barrister Ivor Frank; and lawyer Drusilla Sharpling, a former Chief Crown Prosecutor for London, who has worked as an inspector of constabulary since 2009.

A separate panel, made up of eight members, represents victims and survivors and advises the inquiry on all aspects of its work. There is also a Victims and Survivors' Forum.

Brian Altman QC is lead counsel to the inquiry.

What is the IICSA investigating?

The inquiry's public hearings consist of 14 separate investigations, which are expected to last until 2020.

The inquiry is investigating:

the cases of British children in care who were sent to parts of the Empire including Australia, Canada, New Zealand and what was Southern Rhodesia between 1920 and the 1970s

alleged failings at Lambeth and Nottinghamshire councils; Cambridge House Boys' Hostel, Knowl View School and other institutions arranged by Rochdale Borough Council; the Anglican and Roman Catholic churches; custodial institutions, residential schools, and the support services and legal remedies available to victims and survivors

"areas of contemporary concern" including the internet and organised abuse networks

allegations of child sexual abuse by "people of public prominence associated with Westminster" and claims of cover-ups

allegations against the late Lord Janner, the former Labour peer who in 2015 was ruled unfit to stand trial on child sexual abuse charges

What have we learned so far?

As of June 2019, six of its investigations are complete.

Their conclusions included:

An interim report concluded that common responses to child abuse "deflected responsibility away from perpetrators and institutions".

Image copyright ABC Image caption John Glynn is among the victims of the UK's child migrant policy

Why has the inquiry been controversial?

The main bone of contention in the inquiry's early years was who is in charge.

The first chairwoman, appointed in July 2014, was Baroness Butler-Sloss. However, she resigned just one week later after concerns arose around her links to the establishment - namely her late brother, Sir Michael Havers, who was attorney general in the 1980s.

In September 2014, Lord Mayor of London Fiona Woolf was named the new head, but after disclosing she had been to five dinners with the late Lord Brittan - one of the people facing accusations at the time, which have since been dropped - she quit by the end of October.

In February 2015, Justice Lowell Goddard, a serving judge of the High Court of New Zealand, took over the reins and was in charge as inquiry began hearing directly from victims and survivors. But by August 2016, she had resigned from her post as well due to "compounding difficulties" and her family life.

A number of lawyers have also resigned or been removed from the process.

In November 2016, the largest of the victims' groups involved in the inquiry, the Shirley Oaks Survivors Association, said it had lost confidence in the inquiry's leadership. But despite threatening to pull out of the inquiry, they remain core participants.

A legal case relating to allegations of abuse relating to Lord Janner has been dropped. The case had previously caused hearings to be delayed because of an "overlap" with the criminal investigation. His family have now met with inquiry staff after initially opposing the inclusion of the former politician.

How much is this all costing?

IICSA is funded by the Home Office and spent £36.6m in the 2018/19 financial year. According to the financial report, almost £11m was on staffing, with £10.5m on legal costs.

Previous total annual costs were £28.5m in 2017/18; £20.8m in 2016/17; and £14.7m in 2015/16.

Prof Jay was paid £190,587 in the past financial year, plus £38,398 accommodation allowance.