On Friday 23 April 2021, the Court of Appeal quashed the convictions of 39 former Post Office sub-postmasters for false accounting, fraud and theft with a further 700 overturned convictions potentially on the way after campaigners won a legal battle to prove the Post Office IT was at fault and the computer system on which their convictions were based was flawed.

Described as one of the biggest miscarriages of justice in UK history, the judgment marked the culmination of a 20-year battle for justice for individuals whose convictions were based on incorrect information from the Post Office’s Horizon sales and accounting system, developed by Japanese IT company Fujitsu.

Between 2000 and 2014, the Post Office prosecuted 736 sub-postmasters and sub-postmistresses - an average of one a week – based on accounting anomalies from the Horizon system, introduced from 1999. Some victims went to prison following convictions for false accounting and theft, many faced steep fines and numerous were financially ruined after the system erroneously reported shortfalls, at times amounting to many thousands of pounds. Some victims attempted to plug the gaps with their own money in an often-fruitless attempt to correct the errors.

As the full extent of the technical glitches responsible for miscarriages of justice emerges, the scandal has opened our eyes to the risks posed by blind faith in technology, and the widely-held view that if the computer says no, it must be right. Corporate governance aside, there are big lessons to be learned and warning bells to be sounded about our collective reliance on IT and the assumption that when problems arise, user error must be the culprit. 

Kirstin Gillon, Technical Manager in ICAEW’s Tech Faculty, says the Horizon saga has served as a useful reminder of the need to strike a more considered balance between blind faith in technology and a complete lack of faith in IT. It is a skill to be honed, particularly as our reliance on IT increases and use of automation, artificial intelligence and machine learning ramps up, she warns. 

Use of technology has become so firmly entrenched in business that there is a temptation to blindly assume that any problems that crop up are the result of user error or malicious intent. The reality is that mistakes - whether in system design, data issues, coding errors or even security breaches – can and do happen, Gillon adds. 

“Understanding the role of assurance and having appropriate internal controls and checks and balances in place is really important. It’s about making sure you have the right processes, training and culture so that people are encouraged to raise issues and feel as if they can challenge,” Gillon says. “There are big lessons to be learned from the Post Office Horizon scandal, not least that faith in technology must always be accompanied by a healthy dose of professional scepticism, a questioning mind and human oversight.” 

It’s also about having a more mature understanding of the risks and what can go wrong, Gillon adds. “That’s where the intelligent user comes in. You don’t need to be a coder but having some literacy and understanding of how things fit together can be very useful in terms of asking the right questions.” 

The good news for accountants is that the idea of root cause analysis is at the heart of what they do, Gillon says. “If something isn’t doing quite what you would expect, it’s about making sure you have a grip on what the issue is. If you think something isn’t quite right, you need the processes and that questioning mentality, the right mindset and culture and support in place that allows people to challenge the status quo and voice any concerns they may have. 

But more than flagging the potential limitation of technology, what the Horizon saga has brought home is the impact of these errors on people’s lives, Gillon says. “We see it as a technology problem but there are human beings whose lives have been dramatically affected by this. We need to make sure people are at the centre of what we do. It isn’t just about technology and systems and bugs. At the end of the day, it is about people. I hope that’s something we can take away from the story.”

The Post Office scandal came to light over the last decade through the dogged work of Private Eye magazine, Computer Weekly, and freelance journalist Nick Wallis. Computer Weekly Editor in Chief Bryan Glick told ICAEW Insights: "Technology is amazing and can bring so much benefit to any business. But it's not and never will be perfect. 

“Even if you have a highly robust system that is - for example - 99.999% effective, that still means you could have one in every 100,000 transactions go wrong - a factor that the Post Office refused to acknowledge. No IT system can work effectively without the people and processes around it to identify and understand what happens if things go wrong. The Post Office scandal was a very human failure."