That Private Eye report is shocking. I hope it’s ok to post part of the opening paragraph. It seems important that as many people read it as possible.
On 11 November 2010, a pregnant sub-postmaster from Surrey was driven out of Guildford crown court in a prison van to begin a 15-month sentence for theft. Seema Misra had been convicted of stealing £74,000 in cash from the Post Office branch she ran in West Byfleet even though, in the trial judge’s summing-up: “There is no direct evidence of her taking any money... She adamantly denies stealing. There is no CCTV evidence. There are no fingerprints or marked bank notes or anything of that kind. There is no evidence of her accumulating cash anywhere else or spending large sums of money or paying off debts, no evidence about her bank accounts at all. Nothing incriminating was found when her home was searched.” The only evidence was a shortfall of cash compared to what the Post Office’s Horizon computer system said should have been in the branch. “Do you accept the prosecution case that there is ample evidence before you to establish that Horizon is a tried and tested system in use at thousands of post offices for several years, fundamentally robust and reliable?” the judge asked the jury. It did, and pronounced Seema Misra guilty. In fact, far from being robust and reliable, the Horizon system was full of bugs and glitches. Worse still, the Post Office knew it.
Bloody awful 
This quote from a BBC article also hits hard:
Jo Hamilton, who used to run a sub-post office from her village shop in South Warnborough, Hampshire, told BBC News things started to go wrong in 2005. "I got to the end of one week and I was £2,000 short so I rang the helpdesk and they told me to do various things and then it said I was £4,000 short. "They then said I had to pay them the £4,000 because that's what my contract says - that I would make good any losses. "Then while I was repaying that it jumped up to £9,000." Ms Hamilton said that, by the time the figure reached £36,000, she lied to the Post Office - wrongly telling them the books were balancing just so that she could open the office the next day. As result of that, she pleaded guilty to false accounting. She has been paying back the money ever since.
No wonder we have lost so many small and rural branches over the past 20 years.