What is the Post Office Horizon scandal and how did it happen?
Between 1999 and 2015 an estimated 4,000 branch owner-managers at the Post Office — known as sub-postmasters or sub-postmistresses — were accused of wrongdoing after faulty IT software showed errors in their accounts.
Many were sacked, chased for money, or accused of crimes such as false accounting, fraud or theft. As many as 900 were then prosecuted and 236 sent to prison. Others were ordered to pay back substantial sums of money, leaving them in financial ruin.
Some of the accused have died without clearing their names, at least four are known to have committed suicide and others have been shunned by their communities after being convicted.
In May 1999 Tony Blair, the prime minister, signed off a move from paper-based accounting to the Horizon
