Stephen Moss spends a day on set

When Swansea-born playwright Ed Thomas set about making his first detective thriller series, set in the isolated coastal town of Aberystwyth, he had no idea he was ahead of the Scandinavian curve that would explode cult noir programming. Although a fan of Wallander, his idea – to create four stand-alone films featuring a conflicted police detective roaming an atmospheric woodland landscape that would act as a second protagonist – came prior to all knowledge of The Bridge and The Killing.

For good reason, he hadn't considered subtitling it. Having won funding from Welsh public service broadcaster S4C and BBC Wales to make the series (he ended up, eventually, with a £4.2m budget) Hinterland – or Y Gwyll as it was also known – would be filmed both in the Welsh language, and separately in English.

And while Welsh broadcasters promised to air the series in Thomas' native tongue without delay, there was no guarantee that Hinterland – and even less likely, Y Gwyll – would end up on BBC4, the unofficial home of foreign-language detective drama. So you can imagine how brilliant it must be to hear that not only will Hinterland (meaning the land or district behind a coast) air on the channel this month, it has been picked up by on-demand streaming giant Netflix.

This deal, just announced, follows the acquisition of the show by DR Denmark, the Danish broadcaster behind The Killing, and can only mean one thing: Hinterland has the potential to become a global hit. Netflix will stream the show across North America and Canada, meaning that for the first time, an original Welsh drama will be immediately available to US audiences. It's a great feat for Wales, seeing as Netflix and other online streaming services will not always clamour to acquire established TV successes, instead taking a punt on new shows or creating their own programming (such as House of Cards and Orange is the New Black). Meanwhile, DR Denmark invested its faith in Hinterland before filming was even complete.

But the imminent success of Hinterland begs the question of whether filming an English version was even necessary. Would non-native audiences have enjoyed the series as much in subtitled Welsh as they would in English, as they do other foreign language drama in the genre? In an interview with the Guardian last year, Hinterland's star, Merthyr-Tydfil-raised Richard Harrington (not to be confused with the politician), spoke of Welsh being "more poetic and colourful" as a language, but sparer, meaning that scenes in the Welsh version "can end a lot quicker". And while Welsh brings an almost mythic sort of emotion to the atmospheric landscapes in the series – a staple of the now-established genre – English is said to be better suited to the tropes of detective procedurals.

With a second series of Hinterland already commissioned, the expectation is already there for an international success story. According to S4C and BBC Wales, production will start in September and the show could be ready for broadcast as early as late 2014. "The audience can look forward to more nail-biting, edge-of-seat suspense, more intrigue in that stunning Ceredigion [Aberystwyth's county] setting, and more clues about the troubled mind of DCI Mathias, the man around whom this gripping series is based," said S4C's drama commisioner, Gwawr Lloyd, today. But can they expect to ever see Y Gwyll?

Hinterland starts on BBC4 on 28 April