By Mark Easton
Home editor, BBC News
Three years ago an official inquiry into the treatment of black people within Britain's mental health services concluded that the system was riddled with institutional racism and blamed the Department of Health for ignoring what it called "this festering abscess... a blot upon the good name of the NHS".
Professor Singh has been accused of setting psychiatry back 20 years
But now senior psychiatrists, some themselves from ethnic minorities, are hitting back, arguing that labelling psychiatric services as racist is both wrong and counter-productive.
Professor Swaran Singh, a consultant based in Birmingham says, "the high rates of psychosis and the high rates of detention are not a result of racism", he insists.
The experiences of black people in mental health services are undoubtedly shocking: black men up to 18 times more likely to be diagnosed with psychotic illness than whites and four times more likely to find themselves locked up under the Mental Health Act.
Understandably, for many within the black community the figures are powerful evidence that services are profoundly racist.
Professor Singh's view has seen him accused of setting psychiatry back 20 years, but he is adamant. He says the term "institutional racism" damages the very people it purports to help and "is erroneous and too simplistic an explanation for ethnic differences. What it does is it creates a wall of mistrust between between service users and service providers."
But in the last few months, research by the Institute of Psychiatry in London has turned the argument on its head. The largest-ever study of psychosis tested the theory that psychiatrists wittingly or unwittingly allowed their clinical judgment to be influenced by the colour of their patients' skin.
Researchers removed the ethnicity of a patient from their notes and asked a doctor to assess them. What they found was that psychosis was still diagnosed nine times more often in black people from the Caribbean - almost exactly the same rate as their presence within mental health services.
Professor Robin Murray from the Institute says the evidence is remarkable. "We have pretty well excluded the possibility that this is a result of misdiagnosis", he says.
In fact, the results suggested the opposite. "Psychiatrists in the UK are less likely to diagnose psychosis in somebody who is black than white with the same symptoms", argues Professor Murray.
The real explanation for so many more black people in mental health services, it is claimed, is that they suffer from higher levels of mental illness. The reasons for that are thought to be social: fractured families, exclusion, poor education, unemployment and cannabis use - all problems which particularly affect the black community.
Dr Shubulade Smith says psychiatry needs to focus on causes of mental ill-health
Research also came up with an explanation for the higher rates of detention under the Mental Health Act. Black people are twice as likely as white patients to be referred to a psychiatrist by the police or a court rather than their GP. In other words, black patients arrive in the system when their condition is much more serious, requiring their detention.
According to some psychiatrists, the consequence of wrongly blaming racism for black people's high representation in mental services is that the real causes of mental ill health in the black community are ignored.
Just as concerning is the claim that some dangerously ill black patients are discharged into the community because white mental health tribunals are worried they may be accused of racism.
Dr Shubulade Smith, a consultant psychiatrist at the world-famous Maudsley Hospital in South London says an all-white panel wouldn't listen to her arguments about one of her black patients.
"He was really at risk getting hurt because of the illness that he had, and the tribunal discharged him", she says. "I don't know what was going on in their minds other than they were too scared of thinking that they might be being racist towards him.
"Racism remains a problem for black people," she says, "and undoubtedly is one of the reasons why there are more black people involved in psychiatric services in the first place, but psychiatry is not where the problem starts."