Britain's troubled inquiry into child sex abuse has been thrown into doubt as New Zealand high court judge Dame Lowell Goddard became its third chairman to resign.
Dame Lowell said the investigation has struggled to shake off its "legacy of failure" with her shock resignation leaving abuse victims fearing there may be delays to the long-awaited inquiry.
Dame Lowell, 67, who was appointed in April 2015, had spent more than 70 days working abroad or on holiday during her time in charge. An inquiry spokesman said she had spent 44 days in New Zealand and Australia on inquiry business and was entitled to 30 days' annual leave.
She did not give full reasons for leaving but in a statement said that accepting the job had been "an incredibly difficult step to take, as it meant relinquishing my career in New Zealand and leaving behind my beloved family".
The inquiry has been beset by setbacks since it was set up in 2014 amid claims of an establishment cover-up following allegations that a paedophile ring operated in Westminster in the 1980s.
In a statement, Dame Lowell 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.
"While it has been a struggle in many respects, I am confident there have been achievements and some very real gains for victims and survivors of institutional child sexual abuse in getting their voices heard.
"I have nothing but the greatest of respect for the victims and survivors, and have particularly enjoyed working with the Victims and Survivors Consultative Panel which I established."
Dame Lowell stated her resignation was "with immediate effect" as she quit in a resignation letter to Home Secretary Amber Rudd on Thursday afternoon.
Ms Rudd said the inquiry would "continue without delay" and a new chairman would be found.
She described the inquiry, which has launched 13 investigations including strongly-denied claims linked to Lord Greville Janner, as the "most ambitious public inquiry ever established in England and Wales".
In accepting Dame Lowell's resignation, she wrote : "I know how personally committed you have been to ensuring that the inquiry is a success for those at its heart: the survivors and the victims.
"You have consistently demonstrated your desire to leave no stone unturned in order that the voices of those victims might be heard.
"It is a testament to your commitment that you have taken the difficult decision to stand down now, having set the inquiry firmly on course, and allow someone else to lead it through to the end. With regret, I agree that this the right decision."
A National Society for the Prevention of Cruelty to Children spokesman said: "Whatever the reasons for Judge Lowell Goddard's decision to stand down it is essential that the inquiry continues with minimum disruption and a replacement chair is found urgently.
"Victims and survivors have already waited too long to have their voices heard and for the abuse they suffered as children to be acknowledged and believed."
Richard Scorer, specialist abuse lawyer at Slater and Gordon who represents more than 50 victims giving evidence at the inquiry, said: "It is incredibly important for survivors that the inquiry continues so the truth is uncovered and their voices are finally heard. It is crucial that the Home Secretary appoints a new chair as soon as possible so this can happen."
Baroness Butler-Sloss stood down in July 2014 amid questions over the role played by her late brother, Lord Havers, who was attorney general in the 1980s.
Her replacement Dame Fiona Woolf resigned following a barrage of criticism over her "establishment links", most notably in relation to former home secretary Leon Brittan, who died in 2015.
The inquiry's terms of reference say that its purpose includes considering "the extent to which state and non-state institutions have failed in their duty of care to protect children from sexual abuse and exploitation".
Lord Janner, who died aged 87 in December, is alleged to have abused children over a period of 30 years, with offences said to have taken place in children's homes and hotels.
Some of Lord Janner's accusers have started civil proceedings to sue his estate, according to his son Daniel Janner QC.
Mr Janner told the Press Association: "I was about to demand Justice Goddard's resignation tomorrow as she had refused my application last week to adjourn the inquiry pending the civil proceedings.
"The obscenity of a proxy prosecution against a dead and innocent man who cannot defend himself must stop.
"This is a manifestation of a national frenzy. My late father is not an institution and Goddard was set up to look at institutional failings.
"We are not even given the right to cross-exam in the Goddard inquiry which is why we refused to participate.
"We now seek justice in the civil proceedings."
Labour MP Keith Vaz, chairman of the Commons Home Affairs committee, said the decision to quit was "astonishing".
He said: "This is the third head of the inquiry who has now resigned.
"Serious questions need to be asked about why the Home Office has not monitored events more carefully.
"We will expect a full explanation from both the Prime Minister and the new Home Secretary about these matters. We need to examine again the remit, cost, purpose and ambition of what the inquiry was tasked with."
Tom Watson, deputy leader of the Labour Party, said: "In the months that Justice Goddard has been leading the Independent Inquiry, hundreds of survivors of appalling sexual abuse have come forward to tell of their experiences. They must be assured that the process will move forward.
"We must not let our failure to find a judge with the relevant knowledge and the necessary staying power deter us from progressing with this complex and demanding task.
"I hope the new Home Secretary will not attempt to take control of the investigation. The independence of this inquiry must not be compromised by ministers or officials.
"The Government must find a new chair as a matter of great urgency."