Two years ago File on 4 investigated how a computer system, called Horizon, was behind what has now become one of the biggest miscarriages of justice this country has ever seen. Hundreds of innocent postal workers wrongly accused of stealing money from their branches by the Post Office itself. Many faced financial ruin, some even went to prison. Since that programme, dozens have had their convictions overturned, and the Post Office has pledged to provide ‘full, fair and final’ compensation to those affected, at the cost of hundreds of millions of pounds to the taxpayer. In this episode, Hayley Hassall revisits the victims she spoke to in 2020 who say they are still fighting for justice - and investigates what the Post Office really knew as this scandal unfolded, as it ruthlessly pursued and prosecuted its very own workers. Reporter: Hayley Hassall Producer: Mick Tucker Editor: Maggie Latham