Cressida Dick once said she was “absolutely outraged” by the depiction of police corruption in Line of Duty. That being so, the Metropolitan Police commissioner will not have enjoyed last week’s report into the murder of Daniel Morgan and the five failed police inquiries which followed.

The 1,200-page report by an independent panel shocks twice over. First, it sets out in remorseless detail how Morgan’s family were failed by corruption and incompetence. But more troubling today is the finding that the Met’s continued instinct to place “concern for its own reputation above the public interest” is a form of institutional corruption.

The case dates back to March 1987 when Morgan, a private investigator, was found dead in a pub car park with an axe embedded in his head. From the outset, the investigation was a shambles. Forensic evidence was not secured, information was lost and leaked. The report notes that a police officer who led a key search of Morgan’s office was a business associate and later colleague of the dead man’s business partner, the man who soon became the chief suspect. The case threw a light on police officers selling information to security firms and the media and abuses kept quiet by a “blue wall” of silence.

The case remains unsolved. In 2011, the Met acknowledged “police corruption in the original investigation was a significant factor in this failure”. The fiasco culminated, years later, in the main suspects securing six-figure damages after their acquittal amid massive process failures and evidence of the coaching of witnesses.

But if the case is unique, the aftermath is familiar. Through the Hillsborough disaster, where police smeared victims to cover up mistakes, the Stephen Lawrence case which led to a finding of institutional racism within the Met, and the circumstances of the 2009 death of Ian Tomlinson, a bystander near a G20 protest, a pattern of obfuscation and cover-up emerges. Then there was the slapdash investigation into phone hacking at a time when links between the police and the Murdoch press were uncomfortably cosy.

It comes as faith in the police is falling. Recent polling shows only 6 per cent of adults have “a lot of confidence in the police” to deal with crime. That falls to 3 per cent in London. Nationally, 48 per cent have a broad degree of confidence, but in London that falls to 36 per cent. Other surveys show low faith over tackling crimes against women and among some minority communities.

Though contrite, the Met prefers to talk of “rotten apples” than a deeper malaise. It also argues that the Morgan case belongs to a different era. The report swats away some of that defence, arguing that the force did not approach scrutiny “in an open, honest and transparent way”. At times its dealings with the Met “resembled police contact with litigants rather than with a body established by the home secretary”.

One example came when the Met blocked unfettered access to its national computer, Holmes. The panel was then told it would cost £26,000 to get a secure laptop; then £65,000; then that its offices needed thicker walls and reinforced windows. At an early meeting, Dick told the panel it was “not there to give a view on how well or badly the investigation was run”.

A perennial problem has been government reluctance to take on the police. They remain arguably the most unreformed public service. In recent times Theresa May has been the only home secretary ready to take action, ordering the Morgan report and creating a new offence of police corruption.

The current home secretary, Priti Patel, by contrast prides herself on supporting the police. But even she was troubled by the tone-deaf response in which Dick simply rejected the suggestion both of lack of co-operation and the finding of “institutional corruption” — a phrase with intentional echoes of the Lawrence inquiry. The commissioner has in effect been sent off to try again.

This comes at a time when the police are seeking ever greater powers. The Met is pressing ahead with live facial recognition technology, while Patel is legislating to give police more power to break up or prevent protests.

This report should be cathartic, but the police’s instinct may be to tough it out on the probably correct judgment that Patel will shy away from a confrontation. This would be a mistake. The police need public trust. They should heed the criticism along with calls for a more powerful watchdog, additional protection for whistleblowers and more resources to fight corruption.

No one doubts the dangers and difficulties of policing. Few of us can understand the stresses of a job where an everyday mistake can cost or ruin lives. One must also acknowledge work to clean up the force. There will always be errors and incidents of corruption. But the true test is how they are handled and the conclusion remains “not well”. The report shows a service yet to accept that sunlight is the best disinfectant.

If Dick wants people to resist the admittedly overblown Line of Duty narrative, perhaps she should reflect on the report’s call for a new statutory duty of candour to be imposed on the police. That, after so many scandals, it should still be felt necessary to legislate to ensure the nation’s law enforcers tell the whole truth and nothing but the truth, speaks volumes.

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