The story of the Post Office IT scandal has gained new momentum in the wake of an ITV dramatisation about how dozens of subpostmasters were falsely accused of theft and fraud and hauled through the courts. After 20 years, campaigners won a legal battle to have their cases reconsidered and in 2019 the Post Office lost a High Court battle and agreed to pay nearly £60 million to more than 550 of its staff. Some ended up in prison, others bankrupt - many more have been left with their health and reputations in ruins. A public inquiry is ongoing, but many victims are still fighting to have their convictions overturned or to secure full compensation.

In this episode of File on 4 - updated since its first broadcast in February 2020 - Hayley Hassall meets some of those whose lives were destroyed. She returns to the Post Office in the East Riding seaside town of Bridlington with former subpostmaster Lee Castleton. There are still buckets and spades in the otherwise empty shop - a business he'd taken on after deciding to give up his job as a stockbroker for a better quality of life. She hears from Tracy Felstead who was convicted of fraud and sent to Holloway Prison when she was just 19 years old.

One whistleblower reveals how he warned the Post Office the Horizon system was unsafe and, in his first ever interview, forensic accountant Ron Warmington reveals how he struggled to get straight answers from Post Office management after he was brought in to carry out an investigation.

Reporter: Hayley Hassall