Actor Will Mellor has said his decision to play Lee Castleton in Mr Bates vs The Post Office was “scary”, as he knew the former subpostmaster would be watching.

Mellor, 48, was speaking on BBC Breakfast alongside Stephanie Gibson, a victim of the Horizon IT scandal, who will feature in the Surviving The Post Office documentary, hosted by Mellor.

More than 700 workers were prosecuted by the Post Office and handed criminal convictions between 1999 and 2015, as Fujitsu’s faulty Horizon system made it appear as though money was missing at their branches.

Hundreds of victims are still awaiting compensation, despite the previous government saying those who have had convictions quashed are eligible for £600,000 payouts.

Mellor said he had been inspired to host the documentary after he became “frustrated” that it took a drama series to bring the scandal to wide public attention.

A man in a blue suit
Lee Castleton, who was played by Will Mellor in Mr Bates vs The Post Office (Yui Mok/PA)

He said: “Playing a real person has its different challenges and it’s scary as well, because you know that the person is going to be watching it.

“But we couldn’t have imagined the impact Mr Bates was going to have on the nation.

“I’m so proud to have been in it, and a bit frustrated that it took a drama to really make the difference, but I’m so happy that we’ve done it.

“There was a lot of pressure to do it, when we were reading the script, we were like, can you believe this really happened? That they actually did this to people, and where’s the humanity?

“I’m really glad that I’ve had a chance now and been given a platform to be able to give other people like Stephanie a voice to be able to try and move on, and get closure.”

In the documentary Gibson speaks about the abuse she received after being accused of theft, saying bricks were thrown through her window and paint stripper was poured on her car.

Mellor added: “When we did the drama, Lee Castleton, who I played, he was telling me, we’ve been trying to be heard for years and nobody was listening, and now because of the drama we’ve got a voice.

“I was thinking there must be so many other people out there who haven’t had a voice, who haven’t had a chance to speak and tell their story, and hopefully we can get some justice for these people.

“That’s what this documentary is about, Surviving The Post Office, and I’m so proud of it. Some of these stories are horrendous, their lives were turned upside down, and their kids and their families.

“It’s not just about the people who were accused.”

In the documentary Gibson returns to the street in South Pelaw, Co Durham, where she used to live, before she felt forced to leave by bullying.

She greets an old friend who tells her she is “always welcome” and that villagers have been following her story.

Surviving The Post Office is available to stream on BBC iPlayer and will be shown on BBC One at 8.30pm on Mondya. There will also be a five-part podcast on BBC Sounds.

Mellor has also starred in series such as Coronation Street, Broadchurch and Two Pints Of Lager And A Packet Of Crisps. He was also a contestant on series 20 of Strictly Come Dancing.