"Physical and sexual abuse on an industrial scale" went "unchecked for decades" at children's homes in a south London borough, a victims' report says.
The report detailing claims by 600 people will go before the Independent Inquiry into Child Sexual Abuse.
At a preliminary hearing earlier, the Shirley Oaks Survivors Association was given "core participant status".
Its leader Raymond Stevenson said child abuse in the Lambeth Council-run homes had been a "reversal to the dark ages".
The abuse had resulted in the "shedding of thousands of tears", he said, and called it a "shame on the establishment" and "institutionalised evil".
The Shirley Oaks survivors accused the police of failing to deal with the allegations adequately, resulting in a cover up.
It is alleged two convicted children's homes abusers were volunteer police officers.
The group said it might request several barristers and solicitors to reflect the number of complainants it was representing, the High Court heard.
It plans to make a formal presentation to the wide-ranging inquiry chaired by Justice Lowell Goddard, along with providing video evidence from members.
The counsel to the inquiry, Ben Emmerson QC, told the hearing, at Royal Courts of Justice, the investigation would be "extremely complex... spanning many years and many institutions in Lambeth".
It is one of 13 initial inquiries announced, including investigations into abuse within the Church, allegations against the late peer Lord Janner, abuse at children's homes in Rochdale and claims of a Westminster paedophile ring.
Who is Justice Goddard?
- Born in Auckland, New Zealand, Justice Lowell Goddard is leading the Independent Inquiry into Child Sex Abuse into historical child sex abuse in England and Wales
- Third person to be appointed chair of the inquiry since it was set up in 2015
- Serving judge of the High Court of New Zealand and UN committee member with experience of working with victims of sexual assault
- In 2007, she was appointed chairwoman of New Zealand's Independent Police Conduct Authority
Mr Emmerson said in the case of Lambeth, there had been claims that a former Labour minister, Lord Paul Boateng, had been named as an associate of one abuser, John Carroll, who was convicted in 1966 and 1999 of multiple charges.
The BBC's Newsnight programme recently presented information suggesting that Lord Boateng visited the Angell Road children's home, run by Mr Carroll, signing a visitors' book.
It also claimed someone identifying himself as Lord Boateng asked if he could help to resolve a row which followed Carroll's application to foster children.
Mr Emmerson said no evidence received by the inquiry so far suggested any impropriety on Lord Boateng's behalf. The peer denies knowing Mr Carroll.
A key aspect of the inquiry will be whether an organised paedophile ring infiltrated both the children's homes at Shirley Oaks, and Lambeth Council's social services.
Mr Emmerson said there was evidence a second paedophile lived at Mr Carroll's Angell Road home, when he was running it, and that a third paedophile, Leslie Paul, was employed in children's services at the same time.
Paul was convicted in December of what a jury heard was "vile group sexual abuse".
The Lambeth inquiry will examine the actions of police, prosecutors and the Department of Health, and assess a number of past inquiries into the allegations.
The inquiry is considering to what extent hearings should be televised.