Mr Bates Vs The Post Office | Preview (ITV1)

A new four-part series written by acclaimed screenwriter Gwyneth Hughes tells the story of one of the greatest miscarriages of justice in British legal history.

Hundreds of innocent sub postmasters and postmistresses were wrongly accused of theft, fraud and false accounting due to a defective IT system - many of the wronged workers were prosecuted, some of whom were imprisoned for crimes they never committed, and their lives were irreparably ruined by the scandal.

Toby Jones will play Alan Bates while Monica Dolan, Julie Hesmondhalgh, Alex Jennings, Ian Hart, Lia Williams, Will Mellor, Clare Calbraith, Shaun Dooley, Amit Shah, Lesley Nicol, Adam James and Katherine Kelly also join the cast.

Between 2000 and 2013, the Post Office held thousands of its own sub postmasters and postmistresses liable for financial discrepancies thrown up by Horizon, its hugely expensive but unreliable computerised accounting system.

Despite warnings that the system was flawed, the Post Office relentlessly pursued the sub postmasters and postmistresses, telling many of them that they were the only ones having problems with Horizon.

Of those affected by the faulty IT system, 736 were prosecuted and hundreds more lost livelihoods, homes and life savings because they paid back money that the Post Office claimed was missing.

Several went to prison - some while pregnant or with young children - many were shunned by their communities, and some have since died before they could find any justice.

The drama will tell how, in 2009, a group of sub postmasters from across the UK decided that enough was enough and formed the Justice For Sub postmasters Alliance.

Mr Bates Vs The Post Office begins Monday 1st January at 9pm on ITV1.