When Swaran Singh, professor of psychiatry at the University of Warwick, received an invitation to a conference on race equality in healthcare last summer, he wrote to the organisers to tell them they were presenting a "one-sided ideological view".
This was particularly important, he said, as the conference was a Westminster briefing where practitioners and academics would discuss policy with key government figures.
"I asked them to have an alternative view represented, but they declined," Professor Singh told Times Higher Education.
The alternative view he believes should have been heard is that racial differences in the incidence of psychiatric disorders and experiences of healthcare are not a result of racism.
Over the past 30 years, many studies have shown that people of African-Caribbean origin are more likely to be diagnosed with schizophrenia and admitted to hospital.
This finding is often attributed to institutional racism in the UK's psychiatric services.
In 2003, the chair of an independent inquiry into the case of David Bennett, a black patient who died while sectioned at a Norfolk clinic, condemned racism within Britain's mental health services as a "blot on the good name of the NHS".
Two years later, the government's five-year plan, as laid out in Delivering Race Equality in Mental Healthcare, demanded "ministerial acknowledgement" of the problem.
A more recent strategy document, New Horizons, says the roots of inequalities in mental health "lie in social, not biological, factors". It followed the Aetiology and Ethnicity in Schizophrenia and Other Psychoses (Aesop) study, an undertaking by the universities of Bristol, Cambridge, Nottingham and King's College London. The study concluded last year that there was a "marked excess of psychotic illness in African-Caribbean and black African populations in the UK". It also found African-Caribbean patients had "more negative experiences of services, leading them to disengage and resist intervention in the event of relapse".
Several organisations, including the Afiya Trust campaign group, said Aesop's conclusion about the excess of illness risked stigmatising African-Caribbeans: the research has been cited by the British National Party.
But such attitudes inhibit research into racial differences in mental health, Professor Singh said, adding that his own review of compulsory detentions found no evidence of institutional racism.
'You can't prove a negative'
In a recent article in the British Journal of Psychiatry, he argues that "despite substantial concern that biomedical differences between ethnic groups can be misinterpreted as innate genetic differences, few would argue that race and ethnicity should be completely abandoned as descriptive variables in research".
Studies should be endeavouring to "unpack" and isolate biological, cultural and social influences of aetiological importance within and between ethnic groups, he says.
The government has invested millions of pounds in initiatives to combat the effects of institutional racism in psychiatry, he added, while sceptical voices are not being heard.
"You can't prove a negative. And nobody ever got a grant by saying: 'Life is complicated and there are no simplistic answers to complex questions,'" he explained.
In 2006, the professor published a paper in the British Medical Journal on the issue. In it, he warns that fear of being accused of racism could prevent psychiatrists from making appropriate clinical decisions and notes that "repeated charges of racism act as a self-fulfilling prophecy by increasing ethnic-minority patients' mistrust of services".
The paper led some to question his integrity, a response he called "entirely political". He added: "Vociferous opinion leaders with an interest in keeping the focus on racism have been able to silence debate by insinuating that to even question the charge of racism is racist."
Professor Singh stressed that he had never denied that racism existed. "I have experienced it myself personally and institutionally," he said, recalling an assault by three white youths who thought he looked like Saddam Hussein.
But he was adamant that "attributing an all-explanatory power to racism is not only erroneous, it also hinders our understanding of the real causes of such difference".
His opponents argue that the recommendations of the Bennett inquiry and Delivering Race Equality should be implemented in full before more research is done.
There is a "huge body" of evidence that such racism exists, said Matilda MacAttram, director of the Black Mental Health charity, so "more theories aren't needed".
Suman Fernando, senior lecturer in mental health at the University of Kent, said the 2006 BMJ article "gave the establishment a way out" by denying the effects of racism. Psychiatric diagnoses are subjective, he argued. "They depend so much on perception of people derived from stereotypes."
Frank Keating, senior lecturer in health and social care at Royal Holloway, University of London, agreed with Professor Singh that race is not the only causal factor in diagnostic disparities. But he said: "If you're going to study black and minority ethnic communities, you have to look at the contemporary and historical contexts - and it's going to get political. You can't avoid that."