The whistle-blower at the centre of a "shocking" case of abuse of adults with learning difficulties first raised his concerns in October, it was reported today.
The Government has ordered a report into how warnings of systematic abuse towards vulnerable adults at Winterbourne View residential hospital, in Bristol, were not acted upon by local authorities and England's social care regulator the Care Quality Commission (CQC).
The former nurse at the hospital has been named in reports as Terry Bryan. Despite contacting the care home's management and the CQC on several occasions his concerns failed to be followed up.
A BBC Panorama team carried out five weeks of undercover filming at Winterbourne View in February and March, which saw patients being pinned down, slapped, doused in cold water and repeatedly taunted and teased.
Mr Bryan, a senior nurse, is reported to have started work at the Winterbourne View residential hospital last August.
He became concerned about the standard of care and complained to the home's managers in a four-page e-mail in October, but when managers failed to address his concerns he resigned.
According to The Daily Telegraph, he wrote in the four-page email: "Certain established staff members seem to relish restraint procedures.
"I have witnessed some with smiles on their faces as they restrain people. I see scant regard for the person's feelings whilst they are being held... and definitely no empathy."
The hospital's owner's, Castlebeck, confirmed a former nurse had made a complaint about the quality of care to hospital managers but neither the chief executive nor board members were made aware of it due to "delays".
Turning to the social care regulator, Mr Bryan raised the issues with the CQC in December asking them to get in touch about serious abuse taking place at the home.
Despite trying to contact the regulator several times, he received no response and in frustration took his concerns to the BBC's Panorama.
The CQC yesterday issued an "unreserved apology" after admitting it failed to respond to at least two warnings from a former nurse about the treatment of patients.
CQC chairman Dame Jo Williams, confirmed that a former nurse had contacted the CQC at least twice to complain about treatment of residents at the hospital, but said inspectors did not attempt to speak directly to the whistle-blower because it was assumed that any problems would be picked up through normal safeguarding procedures.
Describing the case as "dreadful and unacceptable", Dame Jo yesterday told BBC Radio 4's PM programme: "We clearly missed an opportunity to talk with the person who was whistle-blowing, to understand the concerns and to fully investigate them, and I am absolutely determined that we must do better."
She added: "We are doing a thorough root-and-branch investigation into what went wrong. We have to make sure that when people are brave enough to raise their voices, we respond in a way that is appropriate."
Care services minister Paul Burstow described the case as "shocking" and said he was "determined to strengthen the system of safeguarding to protect vulnerable adults from abuse".
The minister said he had ordered a "thorough examination" of the roles of both the CQC and the local authorities in the case and asked the care regulator to undertake a series of unannounced inspections of similar services.
Avon and Somerset Police have arrested and bailed three men, aged 42, 30 and 25, and a 24-year-old woman following the secret filming.
Thirteen members of staff, including two managers, have been suspended by the hospital's owners Castlebeck.
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