TV drama The Man In The High Castle, where Nazis won WWII

Rufus Sewell in The Man in the High Castle. Picture: PA

In our world of instant online reaction, putting any TV show in the hands of us viewers to rate and slate can be a daunting task for those involved.

But the cast and crew of new sci-fi drama The Man In The High Castle threw themselves head first into a very public popularity contest earlier this year, when the series - initially a “dead project” according to the show’s writer Frank Spotnitz, having been rejected by other broadcasters - was made available on Amazon Prime to stream.

“What’s different on this occasion is that public voting and viewer numbers decided whether or not it would go on [to have a full series],” says British actor Rupert Evans, who plays American jewellery designer Frank in the show. “So we were very lucky to be the most popular pilot on Amazon. We were relieved and very happy to make the season.”

Based on Philip K. Dick’s 1962 alternative history novel of the same name, the series imagines a world whereby the Axis Powers won World War II.

Consequently, the United States is split between Imperial Japan on the West Coast and Nazi Germany in the East Coast, with the Rocky Mountains remaining a ‘neutral zone’.

Despite the oppression, there’s a growing resistance movement, as citizens start to reject the regimes.

It was a story that Paris-born actress Alexa Davalos, who plays Juliana, a young woman who becomes interested in the resistance after her half-sister is killed in front of her, found gripping from the off-set.

“It’s fascinating,” says the 33-year-old rising star. “The possibilities of what could have happened if it had gone that way, and how that would have affected our families and everyone else, are endless.”

Fans of 2013 BBC series The Village may recognise Evans, who played blue blooded Edmund Allingham in the period programme.

But with an American accent and thickset glasses, Frank - who is desperate to keep his Jewish heritage a secret, for fear of imprisonment and death - is a world apart from Edmund.

“Frank really is someone who is living his life, keeping his head down and trying to survive in this world,” says the Staffordshire-born 38-year-old. “It’s not until the end of episode one and the start of episode two that you start to see his life turn upside down, and he becomes, in many ways, a sort of extremist or radicalised. That arc for me, as an actor, was incredibly exciting.”

Elsewhere, Rufus Sewell, who you might recognise from 2006 Kate Winslet movie The Holiday, plays SS guard John Smith, and Road Trip star DJ Qualls plays Frank’s colleague Ed McCarthy.

Drama? Thriller? Sci-fi? Counter factual? Yes, The Man In The High Castle is all of those things. “It’s a science-fiction show, an alternative reality show and it’s a period show,” says Evans.

And one which the cast hope will run for a good while yet. “We’re just scratching the beginning with the first season,” says Davalos. “I think Frank’s idea is to be able to stretch it for a long time.”

“I really didn’t know how big the series was,” adds Pretty Little Liars actor Luke Kleintank, who plays double agent and Juliana’s possible love interest, Joe Blake. “It’s like when you see the kids who did The Hunger Games, they didn’t know the scope of it.”

Being available on Amazon, instant feedback - via the internet comment boards - comes with the territory, and Spotnitz makes a point of reading “every single comment” about the series.

“Ten are nice, and then there’s the one that’s so nasty it’s awful,” he says with a laugh. “But I’ve always done that [read the comments], even from the early days of The X-Files, because I think - you’re a storyteller, you’re trying to communicate to people, and I want to know what people are getting out of the script.”

Davalos and Evans, meanwhile, admit they steer clear of reading the comments altogether, and Kleintank taking a less committed approach. “I did it for a little bit, but then I stopped doing it because some people are really mean, and I tend to focus on the bad comments rather than the good ones,” he adds.

Best-known for his work on The X-Files, Spotnitz is already “so excited” to see the return of the Nineties sci-fi series early next year.

“The only bittersweet thing is that we were doing Man In The High Castle literally at the same time as The X-Files, because [otherwise] I would have loved to have been part of it,” he says.

Some of the cast were nearly part of iconic paranormal series, though.

“We were filming in the same town, sometimes only a block away,” says Evans. “In fact, I actually went into their trailers thinking it was our trailers, and I got turned away. It’s a very different show!”

• The Man In The High Castle is available to watch on Amazon Prime Video from Friday, November 20