United Kingdom Home Secretary Amber Rudd says she is taking immediate steps to appoint a new Chair for the independent inquiry into child sexual abuse, following the resignation of New Zealander Dame Lowell Goddard.

In a letter accepting Dame Lowell's resignation, Ms Rudd has said the "most ambitious public inquiry ever established in England and Wales" continues without delay and the UK government's commitment is "undiminished".

Dame Lowell resigned as chair on 4 August 2016 exactly 18 months after the announcement on 4 February 2015 that she had been appointed the third chair. In a statement, Dame Lowell said she had thought "long and hard" about taking on the role.

"It was, however, an incredibly difficult step to take, as it meant relinquishing my career in New Zealand and leaving behind my beloved family," she said.

"The conduct of any public inquiry is not an easy task, let alone one of the magnitude of this. Compounding the many difficulties was its legacy of failure which has been very hard to shake off and with hindsight it would have been better to have started completely afresh."

How did the inquiry begin?

The then British Home Secretary Theresa May (now, of course, Prime Minister) announced the inquiry on 7 July 2014. She told the British Parliament that the government would establish an independent inquiry panel of experts in the law and child protection "to consider whether public bodies – and other non-state institutions – have taken seriously their duty of care to protect children from sexual abuse."

Ms May said the inquiry panel would be chaired by "an appropriately senior and experienced figure" and it would be a non-statutory panel inquiry with access to all the government papers, reviews and reports it needed.

Given the scope of work, the panel was not likely to report before the general election, Ms May said. Hindsight is a wonderful thing.

Was the inquiry something to do with Jimmy Savile?

Following the outing in 2012 of the late and now reviled Jimmy Savile as a child sexual abuser, police investigations uncovered several prominent people who were linked to child sexual abuse. A growing awareness of the ease with which some celebrities had been able to abuse children compounded with emerging evidence of child sexual abuse in a number of institutions, including in the BBC, the NHS, in children's homes and in schools. Added to this were growing reports of failures within the police to investigate allegations of child sexual abuse, and failures within the Crown Prosecution Service to prosecute these allegations.

The British inquiry was instigated by seven MPs who went public with calls for an independent inquiry over and above the various cross-government groups which had been established to tackle the problems. Within a matter of days they had become a cross-party group of over 150 MPs, leading to establishment of the panel of experts. The panel comprised eight experts, along with Ben Emmerson QC as counsel. There were two types of inquiry possible in England and Wales - the more formal "statutory" inquiry under the Inquiries Act 2005, and a non-statutory inquiry, which was the format chosen.

What happened to the first two chairs?

On 8 July 2014, just one day after Ms May's announcement, Baroness Elizabeth Butler-Sloss was appointed to chair the panel of experts. The first woman to be appointed a Lord Justice of Appeal, she retired from the bench in 2005. Interestingly, Baroness Butler-Sloss had headed the inquest into the death of Princess Diana from 7 September 2006 until she suddenly stepped down in June 2007, saying she lacked the experience required to deal with an inquest with a jury. Baroness Butler-Sloss lasted just six days as chair of the panel of experts, stepping down on 14 July 2014. The problem was that her brother had been Attorney-General while some of the abuses occurred and this resulted in widespread pressure from victims' groups and MPs who believed this rendered her unsuitable to be chair.

After a couple of months, on 5 September 2014, prominent solicitor and Lord Mayor of London Fiona Woolf was appointed to chair the panel. She lasted a bit longer than Baroness Butler-Sloss, but faced the same pressure from groups who were concerned at her past links with possible inquiry subjects. Not long after media reports that a judicial review of Ms Woolf's appointment had been launched by a victim of historical child sex abuse, she stepped down as chair on 31 October 2014.

It was clear that any further chair of the panel would have to be free of any possible links to the British establishment. The Home Office criteria for selecting the chair specified the usual attributes of experience, leadership, respect, authority, objectivity, professionalism and resilience. There was also a due diligence process which required an extensive check to make sure the appointee had "no personal links to those who have been convicted, or are subject to police investigation, of child sexual abuse", as well as no direct links to key institutions or individuals reasonably likely to be covered by the inquiry. Given the rumours and allegations of widespread child abuse, it became clear that the search for a chair probably had to take place outside the United Kingdom.

On 4 February 2015, just over three months from the resignation of Fiona Woolf, Dame Lowell was announced as the third chair of the inquiry.

What happened to the panel of experts?

With the departure of the second chair there was a major reappraisal of the powers required to produce an effective outcome. Along with the appointment of Dame Lowell in February 2015 it was announced that the inquiry would now become a statutory inquiry pursuant to the Inquiries Act 2005. The existing panel of experts was disbanded and after a period of recruitment and establishment, the Independent Inquiry into Child Sexual Abuse really only started operations on 9 July 2015.

The Inquiries Act is relatively new, partly being introduced to place some controls on the way inquiries are managed after the 12-year Bloody Sunday inquiry which ended up costing £192 million. An assessment of the 2005 legislation in the Law Society Gazette on 27 March 2014 noted that the only significant differences between a 2005 Act inquiry and a non-statutory inquiry are the powers to compel the giving of evidence, take evidence on oath, and the presumption that hearings will be public. Between 2005 and 2014 there were just 14 public inquiries under the Act.

So, what exactly is the objective of the statutory inquiry?

The terms of reference say the purpose of the inquiry is "To consider the extent to which State and non-State institutions have failed in their duty of care to protect children from sexual abuse and exploitation; to consider the extent to which those failings have since been addressed; to identify further action needed to address any failings identified; to consider the steps which it is necessary for State and non-State institutions to take in order to protect children from such abuse in future; and to publish a report with recommendations."

The inquiry is given extensive powers to achieve its objective, with requirements of transparency. It must cover England and Wales and state and non-state institutions including government departments, the police, churches, political parties and the armed services. It has "full access to all the material it seeks" and must refer any allegation of child abuse it receives to the Police. For the inquiry's purposes, "child" is anyone under the age of 18, but it may consider individuals over that age if their abuse started when they were a minor.

The work has been planned in three broad directions:

• Public hearings into specific areas of concern. These will take the form of a conventional inquiry, with witnesses giving evidence on oath and subject to cross-examination.

• A research project is analysing existing published work which addresses institutional failures in child protection.

• The "Truth Project" will seek to get victims of child sexual abuse to share their experiences with the inquiry either in private interviews or in writing.

How long is this going to take?

The terms of reference require the inquiry to produce regular reports and an interim report by the end of 2018.

"Staggering", "ambitious" and "mind-boggling in its scale and scope" have all been used to describe the task before the inquiry. "[Dame Lowell's] terms of reference mean she will have to examine the causes and effects of child abuse in all state or non-state institutions, as far back in history as required. That could take 10 years. No-one really believes the official estimate, that it could take five," said BBC correspondent Tom Symonds in November 2015. Dame Lowell told the New Zealand Listener on 12 July 2016 that it was "unprecedented in the breadth and scope of its terms of reference, which are the broadest you would ever have seen".

What's been done?

Amongst the media frenzy over Dame Lowell's resignation, child sex abuse campaigner Chris Tuck added a note of perspective in The Guardian on 10 August 2016: "As a victim of abuse and campaigner on this issue, I am personally sad that Goddard has resigned, but feel confident that the inquiry will move forward and do the job that it has set out to do. It is important to remember that the inquiry is not just about Goddard; there are many other people involved and a new chair will be appointed in due course."

While recent comment has noted that not one person has yet been formally interviewed, it is clear that a lot of work has already been completed. Behind-the-scenes work such as setting up offices across England and Wales, preparing a full research strategy and adding an academic advisory board, devising and announcing (on 27 November 2015) 13 separate investigations into a broad range of institutions, seeking views on the effectiveness of criminal and civil compensation systems, establishing a means of gathering and analysing information provided online,  and establishing times and the framework for preliminary hearings into a number of matters - these have all been proceeding. Public hearings are scheduled to being on 7 March 2017.

The many staff and advisers of the inquiry itself are still working away. The chair has a heavyweight panel of advisers, who remain. A statement on 5 August 2016 from the inquiry said: "Investigations, research activity and Truth Project private sessions will continue as planned, and victims and survivors are encouraged to continue coming forward. Those victims and survivors who have already chosen to share their experiences with us continue to make a valuable contribution to our work, which will be carried on as the Inquiry moves forward.

"The appointment of a new Chair is a matter for the Home Secretary.  We are committed to ensuring that the work of the Inquiry continues to be conducted as transparently as possible, and will provide further updates as soon as they are available." 

Are England and Wales the only places with an inquiry such as this?

No. At the moment we have the Australian Royal Commission into Institutional Child Sexual Abuse, the Independent Jersey Care Inquiry, the Historical Institutional Abuse Inquiry in Northern Ireland, and the Scottish Inquiry into Historical Abuse of Children in Care.