As a miscarriage of justice, it is perhaps unrivalled in British history. Between 1999 and 2015, at least 3,500 sub-postmasters were wrongly accused of theft, fraud and false accounting by the Post Office. The fault lay with the defective Horizon IT system, which incorrectly suggested that there were financial shortfalls where none existed.
Trapped in a Kafkaesque nightmare, workers protested their innocence, but this did not stop them being trampled upon. More than 700 sub-postmasters received criminal convictions and 236 were imprisoned. Others were forced to pay back tens of thousands of pounds and suffered financial ruin. Family homes were lost and marriages destroyed. At least four victims are thought to have taken their lives as a consequence.