The ‘Mr Bates vs The Post Office’ writer believed the programme would be a failure.
The ITV drama documents the infamous Post Office Scandal, in which sub postmasters were wrongly accused of stealing from the company and were sent to prison after the new system called Horizon logged incorrect figures.
Writer Gwyneth Hughes admitted she thought the programme would be a flop.
Speaking to Sky News, she said: “We’ve all been blown away by it [the reception].
“On the eve of transmission, our boss sent us all a comforting email warning us that it probably wouldn’t do that well, and probably not many would watch it.
“So we woke up [the] next morning and he literally thought he had misheard the ratings, and it just has got bigger and bigger.
“The whole thing is unbelievable, the story of the postmasters, and what happened to them was completely unbelievable from beginning to end and this is just the latest unbelievable chapter in the unfolding, ongoing story.”
The hard-hitting drama stars ‘Indiana Jones’ actor Toby Jones, 57, as sub postmaster Alan Bates, who campaigned for justice for him and his 700 colleagues who were wrongly prosecuted.
Toby was also blown away by the reception the programme has received, and revealed he accepted a pay cut in order to ensure the show could be made.
In an interview with The Times, he said: “There is a huge possibility that shows like Mr Bates will not be made in the future. Not because TV commissioners don't want them, but because they can't afford them. The financial pressures are too great.
"These kinds of four-part, very British, thoughtful dramas are massively at threat because distributors worry that it is less likely that they will recoup their investment than they would from an international thriller with lots of episodes.”