Today marks an extraordinary two years in which the Independent Police Complaints Commission (IPCC) has been considering, and so far failing even to start, an investigation into South Yorkshire police’s own referral of its conduct during and after the notorious battle at Orgreave during the miners’ strike. Members of the Orgreave Truth and Justice Campaign are marching on the IPCC’s offices in Holborn to “express anger and dismay” that so much time has run away with no firm action by the IPCC.

The referral was for some of the most serious criminal offences police officers can commit: the alleged assault of miners at Orgreave during the mass picket of 18 June 1984, principally battering them on the head with truncheons and then allegedly perverting the course of justice, committing perjury and misconduct in public office in the failed prosecutions of 94 miners for riot and unlawful assembly.

South Yorkshire police referred itself to the IPCC, stating that these offences may have been committed, after the Guardian brought to light the failed Orgreave prosecutions in 2012, followed by a BBC Yorkshire Inside Out documentary.

A freedom of information request to South Yorkshire police has revealed that in the referral to the IPCC the force has considered that the then chief constable, Peter Wright, may have been guilty of perverting the course of justice. As picketing by miners of the Orgreave coking plant increased in May 1984, the referral states that Wright decided to employ a team of detectives to “gather and collate the evidence” to support charges of unlawful riot or assembly – which carried a maximum life sentence.

The force appears to admit one of the central allegations made in the May-June 1985 trial of 15 miners which collapsed, that this team of detectives dictated parts of other officers’ statements, or guided or “assisted” them in making their statements. Michael Mansfield QC, who represented miners in that trial, alleged the dictated paragraphs were intended to set a scene that a riot had been taking place, which could have got men convicted for being part of it despite relatively minor actions of their own.

Miners, fighting to protect jobs in pits that were subsequently closed down after the strike was defeated, were truncheoned over the head, then several spent time in prison on remand, fearing very long sentences, while awaiting trial.

Mansfield at the time described the Orgreave evidence as “the biggest frame-up ever”, having highlighted during the trial other alleged police malpractice: an officer who forged another’s signature on a statement, false evidence against individuals, and general police evidence that misrepresented what actually happened – the claim that miners were rioting before police charged on horses, at a time when official film showed miners mostly relaxing in the sunshine. The miners’ lawyers alleged that two police officers had been allocated to each arrested man, then made near-identical statements that they had seen a miner commit an offence as part of a general riot, which crumbled under cross-examination. Wright himself subsequently said the police case had suffered from difficulties of identifying people – and yet 55 prosecutions were still brought for that most serious offence.

The force’s own referral asks the IPCC to investigate whether Wright may have criminally perverted the course of justice “by manipulating the evidence to substantiate more serious charges than were evident”. It also said the chief constable might be considered to have perverted the course of justice “by instructing officers to complete statements with evidence which is not true”. It says every officer who made a statement that contained untrue evidence may have perverted the course of justice, and some who were witnesses in court may have committed perjury. Misconduct in the public office of a policeman may have been committed by every South Yorkshire police officer involved in any of those activities, the force itself told the IPCC.

It is difficult to think of more serious possible misconduct by police officers, who are entrusted with the vitally important and habitually dangerous job of keeping people safe and protecting society from lawbreaking. In November 2012, nobody would have believed we could arrive at November 2014 and the IPCC would not even have made a decision whether to investigate.

The arguments against investigating, which the IPCC is likely to be considering while it examines the documents that have taken two years to collate, include that all this happened a long time ago, that Wright and others are now deceased, that Mansfield and his colleagues did a good job and no prosecuted miner was actually convicted, and that the truth and justice campaign is calling for a public inquiry into the wider issues of the miners’ strike, which an IPCC investigation into Orgreave cannot satisfy.

The IPCC will weigh up the fact that the evidence did collapse in court, and 39 miners received £425,000 in compensation six years later after suing for malicious prosecution and other civil wrongs, although South Yorkshire police never admitted wrongdoing or liability.

Those, though, seem like seductive get-outs for the IPCC, which is responsible for holding police forces to good conduct of their difficult job. There are significant reasons why a full investigation should be held into what happened at and after Orgreave. It was a seminal confrontation in British social history, a mass force of police taking on a huge crowd of miners, after which trade unions were relentlessly weakened and great industries were closed down.

There are many unanswered questions that are still the source of bitter resentment by the miners affected and the wider communities in large ex-mining areas. Many of the accused miners had their lives ruined even though they were ultimately acquitted, and one defendant, a young man at the time, is said by his former colleagues to have killed himself.

The alleged misconduct, a chief constable of a major force leading an operation to fabricate serious charges, is enormously disturbing. As South Yorkshire police itself has stated that Wright led the operation directly from the top, it may have established and legitimised a criminal culture of fabricating evidence within the force. Neither Wright nor any other officer was ever investigated or disciplined for this alleged “frame-up” afterwards, and so if it did take place as the modern force considers it may have, that criminal culture may have remained and become accepted.

The huge significance of this for public trust in policing seems to balance the evident difficulty that the events and failed prosecutions happened 30 years ago. The scars have not healed, as the South Yorkshire police themselves experience every day, in towns and villages for whose safety they are still responsible. These are, as the Orgreave veterans state in their campaign name, vital matters of truth and justice. So the IPCC must get on and investigate.