The Horizon affair is a human tragedy and an Establishment humiliation.

Without a radical change in mindset at the top of government and the civil service, it will happen again. This sorry episode must be a reckoning for how the state goes about delivering large scale change, and the organisations it partners with.

I have watched the Horizon story unfold for over a decade. The sustained attention it is now receiving is well overdue.

In the early 2010s, I was the UK government’s Chief Digital Officer and running the Government Digital Service (GDS). This was a new team in the heart of government specifically set up to show a different way of working, and stop the state from blundering into more disasters like Horizon. GDS was created in the wake of the NHS National Programme for IT’s £10 billion collapse. This failure, now more than 15 years past, bears similar imprints to what has happened in the Post Office.

Why did this happen again? There is no doubt that as the suppliers of flawed technology, Fujitsu have a case to answer. During my time in government, it was made clear to me that they and the Post Office would be following the same playbook they always had, regardless of how often that had been shown up as inadequate. They had no interest in embracing the new ways of working GDS was advocating for.

But it is important to stress - this is not simply an IT failure or one rogue supplier. This is an organisational and systemic failure. One where senior officials and politicians did not get it right in ways that are predictable and repeated.

Oversight and governance in the departments’ responsible for governing the Post Office (and the Royal Mail previously) should have sounded the alarm far earlier. But they didn’t. I believe one reason they didn’t, based on my Whitehall experience, was that those supposed to be on watch lacked the experience and curiosity required to intervene effectively in technology-enabled programmes. They took the Post Office and Fujitsu at their word, and didn’t know the right questions to ask. Suppliers may occasionally behave badly, but they usually behave rationally. Fujitsu couldn’t have done this if they had been managed differently.

This yawning gap in knowledge and curiosity around technology remains true across senior levels of government, the civil service, parliament, and the judiciary. And it is buttressed by a marriage of convenience between those leaders and large enterprise IT companies like Fujitsu. The consultants offer silver bullets that politicians and senior officials are all too happy to pay handsomely for. When the alternative is for them to engage in wicked problems that are unglamorous, difficult to understand and do their careers little good, many are all happy to hand over cash and control to the contractors.

And who loses out from that arrangement? The users of those systems. Us. Citizens faced with poor experiences at one end of the spectrum; subpostmasters with tragically ruined lives at the other.

And there have been other cases in the UK where the assumption that technology is infallible has led to blameless individuals being prosecuted where it turns out the data was wrong.

In 2013-14, 70 nurses at the Princess of Wales Hospital were suspended as they were suspected of falsifying blood glucose results from patients. Five were charged by police, two went to prison. An expert witness uncovered that the digital records had been affected by the WannaCry cyber attack, and an engineer from the system supplier had accidentally deleted some of the records while making repairs. The IT team at the hospital was aware that this had happened, but the investigation team was not, and proceeded on the basis that computer evidence is always correct. It wasn’t. More ruined lives.

We cannot afford either the human or economic costs of another Horizon happening again. If that is to be avoided, leaders from across the political spectrum need to recognise that the status quo of officials and ministers arguing over policy minutiae while the consultants make hay must stop.

We also need to stop making big bets on enterprise IT, and seductive silver bullets that have a frightening tendency to end up in our own feet. And we need much more of what is happening in a handful of public services: highly skilled, in-house teams, applying the ways of working that birthed the giants of the internet-era, delivering what matters for citizens. Some of these brilliant people are in government, but they are too few and far between. And they are fighting against the tide.

There are more than enough sequels on television these days. Let’s not have another one.