Hit show’s writer “dazed” by the popularity of drama – staring Eve Myles – and her yellow raincoat.
The BBC Wales production has become the broadcaster’s most successful non-network drama in over 20 years.
It has attracted audiences of more than 300,000 on television, with about 9 million BBC iPlayer downloads.
A second series is in development, but has not yet been commissioned. The BBC has yet to confirm if the drama will be shown on network TV across the UK.
Matthew Hall, the Monmouthshire author responsible for the story, said the team behind the drama had been stunned by the audience reaction on social media.
He said: “We’ve all been kind of surprised and a bit dazed by it really.
“The wonderful thing about it is that the most you ever hope for as a writer, or indeed as an actor or director, is to forge an emotional connection with some of the audience. And that is what it seems to have done.
“I think we’re still trying to work out what that is, what they’re responding to.”
While the series has only been shown on television in Wales, audiences across the UK have been watching on the BBC iPlayer.
It has attracted celebrity support, particularly on social media, while the main character Faith’s yellow mac has prompted people with similar coats to post selfies. It even has its own Twitter account, and was worn by BBC Breakfast presenters to celebrate the show’s success.
The series, which was produced by Vox Pictures, was jointly commissioned by the BBC and S4C. It was first broadcast in Welsh with the title Un Bore Mercher on S4C.
Eve Myles learnt Welsh in order to appear in both the English and Welsh language versions of the series, while the action is set around the west Wales village of Laugharne.
Matthew Hall said he had attempted to capture Welsh traits in the show’s characters.
He said: “There’s a sort of Welsh way of conducting yourself which is different to the English way, and we tried to capture that.
“Certainly the Welsh bits of my family are far more emotionally expressive, are more inclined to tell you how they feel. They’re more Mediterranean in temperament almost, and I wanted Faith to be like that. To have this emotional honesty, so what she was feeling came out of her mouth almost.
“So she gives voice to all her insecurities, and to her anger, and I think the audience likes that about her.”
The programme was due to end its run on the iPlayer on 4 May, but the BBC extended its availability across the May bank holiday weekend following increased publicity for the show.