Will Mellor has welcomed the news that former Post Office boss Paula Vennells will hand back her CBE as the “first step” in a campaign to get justice for subpostmasters who were wrongfully convicted.

The actor starred in ITV drama Mr Bates Vs The Post Office, which began airing on January 1 and has shone a light on how people became caught up in money missing from their shops due to faulty accounting software.

He portrayed subpostmaster Lee Castleton, from Bridlington, East Yorkshire, who said he called a helpline 91 times asking for assistance over unexplained losses before he was caught up in a legal battle with the Post Office and went bankrupt.

Mellor told the PA news agency: “We knew it would make a splash of some kind, there’s no way we could have imagined it would have had (this) response, and it’s unbelievable in a really good way, in a positive way.

“I think even though people thought they knew what happened with the subpostmasters, reading it in a newspaper or seeing an article about it doesn’t land as much as when you see it.”

The 47-year-old actor said that the public have gone through the “emotions” of seeing postmasters have their lives upended in the four-part series, which also stars Toby Jones as Alan Bates.

Mellor added: “People are angered by it and they want something to be done, and you’ve seen what’s happened now with the petition and it just shows us how strong we are when we come together.

“The people (are) all coming together and saying: ‘No, we want justice for these people and people need to be held accountable for what’s happened.’ “And I think today is the first step with Paula Vennells handing back her CBE, that’s just the first.

“The most important thing, for me, is to try and get justice for these wrongly accused subpostmasters, whatever that looks like – yes, we want them to get compensation, but what does that look like?

“How much value do you put on somebody killing themselves, losing your husband, losing a loved one, going to prison, losing 20 years of your life to depression, forgetting what your childhood looked like, because you’ve had depression and you’ve had to have treatment for that?

“I mean, what does that look like? It’s a horrendous story, but such a positive outcome from the drama, it’s overwhelming.”

More than 1.2 million people had signed the petition demanding former Post Office chief executive Ms Vennells should be stripped of her honour.

Mellor, also known for his roles in Two Pints Of Lager And A Packet of Crisps and Coronation Street, said the role is “bigger than anything I’ve ever done before”, and all he “needed” was Mr Castleton saying he was happy with the portrayal.

The actor added: “It shouldn’t take a TV drama to make this much of a difference, but I’m glad he did. I mean, where would you be without it?”

Mellor said an apology is not enough for the postmasters, and action, including getting the convictions overturned and compensation, is needed.

He said: “We need to stop these people kicking the can down the road, and get these people what they’re owed.

“We also need to hold people accountable for what they have done to these people.

“You get one life – what price do you put on 20 years (that have) been taken from you?”

On Tuesday, ministers were looking into trying to speed up Post Office branch managers being cleared after more than 700 subpostmasters were caught up in the scandal involving Fujitsu’s Horizon software.

Mellor also encouraged more subpostmasters to come forward.

“Thank you to everybody who has messaged me who’s got in touch, who signed a petition, who supported the show – and it is now supporting the subpostmasters,” he said.