Across four parts, the series told the true story of the more than 900 subpostmasters who were wrongfully prosecuted for stealing from the Post Office because of a faulty computer system called Horizon.

Bolstered by the likes of stars Toby Jones and Monica Dolan, the series so heart-rendingly humanised the horrific miscarriage of justice that, as of late-April, around 13.5 million people had tuned in.

The new documentary will hear from the titular hero Alan Bates and his fellow subpostmasters Jo Hamilton, Jess Uppal and Noel Thomas. They’ll be talking about how the series has affected their lives and their decades-long fight for justice.

ITV will also hear new stories from more suffering subpostmasters, who have only gained the courage to come forward in light of the series and the outpouring of support.

As the Post Office Horizon IT Inquiry continues, the documentary will dissect key moments of the hearings to date. This includes the testimony of former Post Office CEO Paula Vennells, who recently made headlines for crying while giving evidence, as well as those of former director Angela van den Bogerd and the company’s investigators. The subpostmasters have described them as collectively behaving like “mafia gangsters.”

Jo Clinton-Davis, ITV’s Controller of Factual who commissioned the documentary, says: “The Post Office scandal became a genuine national talking point at the start of this year, striking at the heart of the public’s sense of justice. The reverberations have been felt ever since at a political level, but particularly in the lives of those directly affected.

“This film promises to tell the story of what has happened since in their lives, how their fight continues as well as illuminating new layers of this scandal.”