A campaigner and activist against the far right, in April 1979 Peach took part in an Anti-Nazi League demonstration in Southall against a National Front election meeting in the town hall and was hit on the head, probably by a member of the Special Patrol Group (SPG), a specialist unit within the Metropolitan Police Service.

The report was not released to the public, but was available to John Burton, the coroner who conducted the inquest; excerpts from a leaked copy were also published in The Leveller and The Sunday Times in early 1980.

In 2009 Ian Tomlinson died after he was struck from behind by a member of the Territorial Support Group, the SPG's successor organisation; the parallels in the deaths proved to be the catalyst in the release of the Cass report to the public.

[3] Blair was schooled at Colenso College, then studied education and psychology at the Victoria University of Wellington,[1][4] where he co-edited the Argot literary magazine with his flatmate Dennis List and David Rutherford.

[9] He had been arrested previously when campaigning on political issues,[10] and in 1974 he was charged with threatening behaviour after challenging a local publican's refusal to serve black customers; he was acquitted.

Many Sikhs and Hindus left the subcontinent to settle in Greater London, particularly Southall, where shortages of workers at factories, and the employment prospects at nearby Heathrow Airport meant jobs were easily obtainable.

[13][a] Racial discrimination in the workplace was common; 85 per cent of those Asian workers who had been given entry into the UK on the basis of their education or training were employed only in unskilled or semi-skilled roles.

Kennetta Hammond Perry, in her history of post-war immigration, identifies the reasons as being "in part because of perceptions about their level of competence and stereotypes about their ability to speak English".

[21] In June 1976 the racist murder of Gurdip Singh Chaggar in Southall—outside the offices of the IWA—led to the former chairman of the National Front, John Kingsley Read, stating "one down, a million to go".

[14][24][25] Rioting in the area took place between police and Asian youths and members of Peoples Unite, a similar group to the SYM, but consisting of young Afro-Caribbeans.

[28] The SPG comprised police officers capable of working as disciplined teams preventing public disorder, targeting areas of serious crime, carrying out stop and searches, or providing a response to terrorist threats.

It was involved in the Red Lion Square disorders, when Kevin Gately, a student demonstrating against a National Front march, was killed from a blow to the head from a blunt instrument; the perpetrator was never identified.

[28] The former chief constable Geoffrey Dear states that the SPG "might apparently solve one problem but in its wake create another of aggravated relationships between minority groups and the police in general".

[34] In the run-up to the 1979 general election, the National Front announced that it would hold a meeting at Southall Town Hall on 23 April 1979, St George's Day.

[35] Prior to the Southall meeting, similar events had resulted in clashes with anti-racist protesters, including in Islington, north London, on 22 April, and in Leicester the following day.

[51] Four members of the public were allowed into the hall to fulfil the requirements of the Representation of the People Act, but a journalist from The Daily Mirror was stopped from entering because the newspaper was considered to be "nigger loving".

[58][59] The official investigation into Peach's death states that the events leading up to this point, while difficult, were relatively straightforward, but that "further description of what happened" is hampered by "conflicting accounts [that] have been given by private persons and also by police".

[69][70] Sir David McNee, then the Commissioner of the Metropolitan Police, also undertook his own eight-day review of the demonstrations, although he did not include Peach's death as part of his analysis.

"[80] One member of SPG Unit 1-1 was questioned by Cass's team in early June 1979 after the forensic report stated that Peach was probably not killed by a police truncheon, but by a lead-filled cosh or pipe.

[84][85] It later transpired that one officer present at the riots shaved off the moustache which he had that day, while Inspector Murray grew a beard and refused to take part in the identity parades.

[55] Cass's report was accepted by the police as being accurate, and in his 1983 autobiography McNee wrote "when all the evidence was assembled it showed that Blair Peach had died from a blow to his skull.

Michael Dummett, Wykeham Professor of Logic at Oxford University, examining the case for the National Council for Civil Liberties, observes that as only the coroner and police lawyers had copies of the report, "it was impossible for anyone ... [else] to obtain a complete picture of the evidence".

[103] Both pathologists—David Bowen for the coroner and Keith Mant acting for the family—came to the same conclusions: that death was from a single blow, not a police truncheon, but a "rubber 'cosh' or hosepipe filled with lead shot, or some like weapon".

[110] He also wrote to the home secretary, lord chancellor and attorney general, claiming that there was a conspiracy to spread false information about Peach's death; he accused several media outlets, including the BBC, of producing what he described as "biased propaganda".

[110] There were several calls for a public inquiry to examine the circumstances surrounding Peach's death and the role of the police; 79 MPs supported such a hearing, but the government refused to hold such a review.

[117] On 1 April 2009, at the 2009 G20 London summit protests, a member of the Territorial Support Group, the SPG's successor organisation, struck Ian Tomlinson, a newspaper vendor, who collapsed and died.

[87] Angered at the handling of the initial investigation, Murray left the police and joined his brother's jewellery business in Scotland before becoming a lecturer in corporate responsibility at the University of Sheffield.

[43][129] Writing after the release of the Cass report, the leader in The Times opined that following Peach's death, "the Metropolitan Police entered a dark place from which they have been struggling to emerge ever since".

[130] In 2010 Andy Hayman, the former assistant commissioner for Specialist Operations at the Metropolitan Police, wrote that Peach's death brought the service and the SPG into disrepute.

[132] Writing in the light of Tomlinson's death, Philip Johnston, a journalist with The Daily Telegraph, observed that Peach was one in a number of incidents where there had been unwarranted police aggression.