Campaigners are to gather at Sheffield City Hall for a rally to mark 40 years since the notorious “battle” of Orgreave during the 1984-85 miners’ strike, and call for the full truth about the scandal to be addressed. On 18 June 1984, an estimated 8,000 miners who had travelled to picket the plant at Orgreave, South Yorkshire that made coke for the steel industry, were met by massed ranks of 6,000 police officers. With force unprecedented in mainland Britain, mounted police charged their horses at speed into the crowd, and officers using batons and short shields beat many miners over the head. Ninety-five men arrested at Orgreave were charged with unlawful assembly or riot, which carried a potential life sentence. But at the trial in 1985 their lawyers, led by Michael Mansfield, exposed flagrant inaccuracies in police statements and evidence given in court, and all 95 were acquitted. No police officer was ever disciplined or prosecuted for the brutality at Orgreave or the collapsed prosecutions. Four years later, South Yorkshire police were also responsible for the Hillsborough disaster at the FA Cup semi-final in Sheffield, in which a 2016 inquest found 97 people were unlawfully killed due to the gross negligence of the commanding officer, Ch Supt David Duckenfield. But the force mounted a false case to blame the victims, Liverpool supporters. The Orgreave Truth and Justice Campaign (OTJC), formed in 2012, will follow Saturday’s rally by delivering to Labour and Conservative party head offices on Tuesday a report that presents new evidence to support their consistent calls for an inquiry. Drawing on some recently released internal documents from Margaret Thatcher’s government at the time of the strike, the report calls for full answers about how the British police came to adopt such brutal new methods, and the extent of the government’s involvement. In its manifesto this week, Labour promised that, if elected, it would “ensure, through an investigation or inquiry, that the truth about the events at Orgreave comes to light”. The party also committed to introducing the proposed “Hillsborough law”, which Rishi Sunak’s government rejected in December, to “place a legal duty of candour on public servants and authorities, and provide legal aid for victims of disasters or state-related deaths”. Theresa May’s government considered holding an Orgreave inquiry in 2016, but ultimately refused. The then home secretary, Amber Rudd, gave a series of reasons, including that “nobody died” at Orgreave, there was “no miscarriage of justice” and “no certainty” that had the police been held to account, “the tragic events at Hillsborough would never have happened”. However, in 2021, those official reasons were undermined in a book, Diary of an MP’s Wife, by Sasha Swire, who recalled a conversation in 2016 with Rudd over a “kitchen supper”. “Orgreave would slur the memory of Thatcher and the party won’t like it,” Swire wrote of the conversation. Asked by the Guardian if that was accurate, and that was a reason for refusing the inquiry, Rudd replied: “I have no comment to make.” The new OTJC report, seen by the Guardian, includes some findings from Thatcher government documents also featured in a book, Charged: How the Police Try to Suppress Protest, by the lawyer Matt Foot and journalist Morag Livingstone. The report highlights the notorious secretive adoption in 1983 of a policing manual that authorised “unprecedented military-style tactics”, first deployed at Orgreave. The OTJC is calling for answers about the lack of public process in the adoption of the manual, and its apparent secret endorsement by the Thatcher government. Kevin Horne, an OTJC activist and ex-miner who was arrested at Orgreave, said: “Many of us were set upon by police in full riot gear. We were peacefully gathered and wearing T-shirts, jeans and trainers. Ninety-five of us miners were arrested just for being there and charged with either riot or unlawful assembly. “We were all acquitted due to the fabricated evidence and police lies. Neither the government or the police have ever been held to account for what they did to us.” South Yorkshire police said in 2016 they were prepared to cooperate with an Orgreave inquiry, and the force is now working on releasing documents relating to the miners’ strike, expected to take up to two years. A spokesperson said: “It would not be appropriate for the South Yorkshire police of today to seek to explain or defend the actions of the force in 1984 as everyone involved in policing the miners’ strike has long since retired and the information we hold has not been properly assessed.” If Labour is elected, a possible form of inquiry could be the examination of documents by a group of experts, similar to the Hillsborough Independent Panel, whose landmark 2012 report led to a new inquest that produced the unlawful killing verdict. The Right Rev Dr Peter Wilcox, the bishop of Sheffield, has offered to chair a similar panel to investigate the Orgreave scandal, but revealed in 2019 that the Conservative government had declined. Kate Flannery, the OTJC secretary, welcomed Labour’s manifesto commitment, and said campaigners hoped “the true events and actions of the [1984-85] Conservative government” would be acknowledged through an inquiry. “We hope this commitment finally delivers the truth and justice that has been delayed for 40 years and that the Orgreave Truth and Justice Campaign has a voice in the way the investigation is structured and run, so we can ensure the whole truth is understood and recognised,” she said.