The Government must dramatically improve the protection it gives people with learning disabilities in the wake of abuse scandals, an official report will say.
Some 3,500 vulnerable disabled people are still languishing in institutions - 900 more than previously thought - despite a Government pledge to move those inappropriately housed out, the report published on Monday will warn.
Promises to move care from asylums to the community came in the wake of the Winterbourne View scandal, when in 2011 an undercover BBC documentary team filmed abuse of patients with learning disabilities at the private hospital near Bristol.
However, a report by Sir Stephen Bubb, the chief executive of the Association of Chief Executives of Voluntary Organisations, will say the scale of reforms needed are "far more challenging" than originally thought.
And he says he is "shocked" by the way "we as a society have condoned poor or abusive treatment" of vulnerable people.
He will demand the Government appoint a learning disabilities commissioner to champion the interests of vulnerable patients, and for a charter of rights to be drawn up for people with learning disabilities and their families.
Sir Stephen Bubb said: "I am calling for an office of a learning disabilities commissioner to be established.
"Just as a children's commissioner was established following the Victoria Climbie Inquiry, there is a firm argument for establishing this post. It would have a statutory duty to promote and protect the rights of all people with learning disabilities and their families.
"I have spoken directly to people whose experience of these services goes back far beyond 2011 and Winterbourne View. So this report expresses the views and experiences of the people most affected by change.
"I am still shocked by the way we as a society have condoned poor or abusive treatment of some of the most vulnerable people in our society."
He said services in England still have "a long way to go before the system can be trusted, and we still have a long way to go in convincing people with learning disabilities that change will happen".
Sir Stephen, who launches his report entitled Time For Change - The Challenge Ahead, in central London, said an extra 10,000 staff will be needed to support people with learning disabilities in their own community.
And he warned that with at least 1,300 people expected to move out of hospital care by 2019, there is a "critical need" to deliver housing for the vulnerable.
Housing for people with learning disabilities should be exempt from proposed housing benefit caps, the report states.
Jan Tregelles, chief executive of learning disability charity Mencap, and Vivien Cooper, chief executive of the Challenging Behaviour Foundation, said now is the time to restore people's faith in the system.
In a joint statement, they said: "People with a learning disability and their families have endured nearly five years of failure by national and local government, and the NHS to bring about meaningful change for the 3,500 people in in-patient units.
"This has left people often far from home in units where they are at increased risk of abuse and neglect, their families fighting to bring loved ones home.
"This is taking place as the NHS and local government are spending an estimated £600 million a year on buying the wrong kind of care for thousands of people."
They added: "Now is an opportunity to restore faith, where so far there has been repeated failure, and build the community support people with a learning disability and their families want and have been promised."