Video report by ITV News Correspondent Juliet Bremner
One of the largest groups representing abuse victims' in the Child Sexual Abuse inquiry has formally pulled out of the process in the latest setback for the probe.
The Shirley Oaks Survivors Association described the inquiry, the IICSA, had become a "stage-managed event" that enabled "the guilty to wash their dirty hands, whilst the establishment pats itself on the back".
It also described the inquiry's chairwoman Professor Alexis Jay - the fourth person to head the panel since the inquiry was set up in 2014 - as "an uninspiring leader".
In a highly critical statement the group, which represents people affected by abuse at children's homes run by Lambeth council in south London between the 1950s and 1980s, said:
The inquiry, which was set up by Theresa May when she was Home Secretary, has been beset by problems.
This new withdrawal comes two days after it emerged that another senior lawyer at the inquiry had resigned.
Aileen McColgan's departure follows the resignation of the inquiry's senior counsel, Ben Emmerson, and his junior colleague, Elizabeth Prochaska.
Labour MP Lisa Nandy said: "This must be the final wake-up call to the Prime Minister and Home Secretary. It's time for them to get a grip on the serious problems and dysfunction at the very heart of this inquiry."
She called for a "fundamental overhaul" of the probe.
"Now the largest victims' group has withdrawn its support and co-operation, Theresa May can no longer continue to blindly insist she has full confidence in its work just because she set it up and appointed many of the key figures," she said.
But the founder of another support group, the National Association for People Abused in Childhood, warned against allowing the Shirley Oaks group's decision to distract from the inquiry, pointing out that other group's remained involved.
"They [The Shirley Oaks Survivors Association] indicated they were probably going to walk away some time ago, but they are maximising their publicity," Peter Saunders said.
"Whether that's good for child protection, I'm not quite so sure."
Raymond Stevenson, chairman of the Shirley Oaks Survivors Association, said the group's members had voted on Saturday that they no longer wanted to be part of the inquiry.
He said the group had co-operated with a previous inquiry involving the Metropolitan Police and Lambeth Council which identified 50 potential suspects, but led to only three arrests.
"They can do it without us. If they want to do a tick-box exercise, they can sit at their computers and go through the figures," Mr Stevenson said.
"We were persuaded to take part in this because we believed we were going to get justice and to expose what took place in Lambeth. If it's going to be the inquiry which we believe it's going to be, then they don't need us."
The association is now preparing to publish its own report naming 60 people as paedophiles.