> They would have had to explain why stock keeping and accounting was so much less accurate before. They would also have to explain why their staff was supposedly far more delinquent than staff at comparable shops.

Clearly they did not have to do these things.

I don't know, because I don't know if anyone even asked the question.

They did ask those questions, and it was their defense in court in many cases. Unfortunately, due to a few factors - lack of funds for competent defense lawyers (many of the accused had to represent themselves against the huge teams of Post Office prosecutors), insular court process that involved only internal Post Office investigators and prosecutors, false information given by the Post Office to the accused that they were "the only ones having this problem", "say you're guilty of false accounting and we'll drop the more serious theft charge", and finally, the union representing the accused sided with the Post Office and offered no help at all (and, bizarrely, the Post Office was and I believe still is the major funding source for that union... I'll leave you to do the speculation...)

In addition, the Horizon system only offered the accused the "client-side" data, so to speak - they could see what they had inputted and what the system had printed out. They couldn't see any kind of internal transaction data, or what happened to the data once it was inputted. Post Office repeatedly obstructed attempts of the accused, their lawyers, and even the third-party auditor they hired to examine the system for faults to retrieve that data - likely because they knew that handing over that data would immediately show the flaws in the system.

The whole thing just stinks of corruption, to be honest.

Thanks for the info. It's truly shocking what has happened in this case - on so many levels.