In response, the Post Office explained that according to an internal report, its system was effective, but better training and support was still needed. However, that’s not what independent investigators said after taking a look at the software. The experts said that despite the fact there was no evidence of systemic problems with the core software, it still had bugs. For example, one of those bugs led to shortfalls of up to £9,000 at 76 branches – fortunately, the Post Office later made good those losses, so the sub-postmasters weren’t held responsible.
At the same time, in other cases the problem has mostly been with sub-postmasters running the smaller post offices in the United Kingdom and not directly employed by the Post Office. Those had to balance their books through the Post Office’s Horizon computer system that processes all transactions. It has been for years that sub-postmasters claimed they have been wrongly accused of theft after their PCs notified them of shortages up to thousands of pounds.
Thus, the postmasters had to pay up the missing amounts, lost their contracts and even went to jail. The experts explained that the Post Office’s initial investigation couldn’t at first identify the root cause of the trouble, saying that more help should have been given to sub-postmasters having no way to defend themselves. At the moment, some of the postmasters are thinking of suing.