'I felt a sense for the first time," wrote a man called Adrian Tempany after the publication of the independent panel's report into the Hillsborough disaster, "that this tragedy was no longer mine – it belongs now to the nation". Tempany was one of those who survived the human crush in Pen 3 of the Sheffield football stadium that day so long ago in 1989. Many of the 96 died in front of him.

"Unable to move for over half an hour, I was condemned to watch them cry for help, throw up, plead for their lives and die," he wrote. "A heap of corpses piled up in front of me." Over 700 others were injured. Thousands more were scarred emotionally to this day.

Yet in the face of such horror the authorities of the British state failed, egregiously and comprehensively, at level after level after level. When the truth finally emerged – like the sweet silver song of the lark, as the Poet Laureate masterfully borrowed from Liverpool Football Club's anthem – it did so because a small group of activists, burning with a sense of injustice, refused to give up.

The driving motor was the bereaved families, but others were at work, too. One was the academic criminologist Phil Scraton, who spent decade after decade diligently compiling the detailed evidence that has so shocked the nation in recent days. In that time he has produced two major reports and a book painstakingly cataloguing the incident itself, the scurrilous allegations made by the police in the days that followed and the appalling treatment of the bereaved by the political and legal establishment in the years since.

Another was the playwright Jimmy McGovern, whose investigations so frightened the police that he was tailed constantly as he prepared his documentary-drama Hillsborough. Seven years after the disaster, it reawakened the nation to the scandal which had never gone away in Liverpool, a city where solidarity has survived better than in the rest of post-Thatcher Britain. Another was James Jones, Bishop of Liverpool, who oversaw the panel that tirelessly processed almost half a million official documents relating to the disaster with self-evident impartiality and pastoral commitment to his people.

In Parliament last week, the Prime Minister apologised for what he called the "double injustice" of Hillsborough. But the truth is that the injustice done was ten- or twelvefold. Police, ambulance services, football authorities, stadium owner, local council, coroner, prosecuting authorities, two judges and politicians all failed and failed again. Civil, criminal and European law all fell short. Some in authority were not just defective but deliberately obstructive.

So why did state apparatus so totally miscarry? And why has an independent panel been able to turn up the truth? Its chairman has said that panels like his are not just faster and cheaper than judge-led inquiries. They can be far more considerate of victims' needs because they start in a different place.

For James Jones, it started every morning with the photograph he kept on his desk of the stadium at 2.59pm on the day of the disaster, alongside the names of the 96 who died. Judicial processes, he says, tend to distance those most affected. "People with power are often patronising to victims. A culture of blame, liability and litigation conspires against getting to the truth. They certainly conspire against enabling the victim to feel their needs and grief are being respected."

The inability, or reluctance, to begin with people rather than processes and the institutional protection of privilege, is part of what has led to the great decline of trust in Britain today. Hillsborough has focused on the police and the courts. But the same thing has happened with greedy bankers, self-serving politicians and unethical journalists. Yet the Church of England retains a lot of confidence among local communities. "It does not run the risk so much of its people being seen to be on the make," as the bishop put it.

It was that local authenticity and integrity which explains why a handful of concerned citizens succeeded over Hillsborough where the great organs of the British state so lamentably failed. What particularly annoys activists in Liverpool is that many of the facts which drew sharp intakes of breath from MPs last week in the Commons had been in the public domain for years, through Scraton's research and McGovern's drama. The local MP, Andy Burnham, had disclosed the same details of senior policemen ordering the doctoring of the notes of ordinary officers in the Commons a year ago. No one listened.

But the panel's scrutiny of 450,000 documents from over 80 organisations added the detail that made the assertions of bereaved relatives incontrovertible. It also offered new revelations about the ambulance service, and proved that the coroner's 3.15pm cut-off was wrong. It disclosed that many in authority knew beforehand that the stadium was not safe, and showed how the Chief Constable of South Yorkshire used the Police Federation to disseminate untruths.

For years, the establishment sneered that McGovern and Scraton were conspiracy theorists. Now we know that there was indeed a conspiracy, one that may prove to be criminal. We know, not thanks to officials, who see themselves as masters rather than servants of the public. We know, because a bunch of individuals would not take No for an answer. Through them, we have discovered, as the survivor Adrian Tempany put it, how systemically justice can be corrupted – and been reminded that right can triumph over might.