A former senior executive at the Post Office was told by auditors the Horizon IT system was "a real risk", four years before sub-postmaster prosecutions stopped.
Japanese firm Fujitsu s faulty software was behind more than 900 subpostmasters being wrongly prosecuted after shortfalls were incorrectly reported on their accounts.
Latest batch of homes approved for Leicestershire's first 'garden village' leicestermercury.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from leicestermercury.co.uk Daily Mail and Mail on Sunday newspapers.
In an emotional testimony, Ms Vennells said she "loved the Post Office" and worked "as hard as I possibly could to deliver the best Post Office for the UK".