The 'Game of Thrones' prequel: everything we know - from the cast to the plot

Alas, the televised Game of Thrones is now officially over, and HBO's programming president Casey Bloys has said there won't be any sequels (or an Arya the Explorer spin-off).

"Right now, a sequel or picking up any of the other characters doesn't make sense for us," he told The Hollywood Reporter, adding, "I do want this Game of Thrones, Dan and David's show, to be its own thing... I want to let it be the artistic piece they've got."

So, no sequel, but we do know that a prequel is currently being filmed in Belfast. When we travelled around Northern Ireland last month, we met people who were already working on the prequel, which is an official HBO production, with the books' author George R R Martin an executive producer.

Here's what we know so far... 

Who will star in it?

The universe's creator, Martin, has said on his blog that none of the original "characters or actors" will appear in the new show (but speculation suggests the Night King might appear).

Here are the 16 actors who have been confirmed for the show (so, while only some of them are currently household names, it's likely that these people will all be superstars in the future):

What will the sequel be about? 

In an interview with Entertainment Weekly, Martin said that the prequel will be set around 5,000 years before the events of Game of Thrones.

"Westeros is a very different place. There's no King's Landing. There's no Iron Throne. There are no Targaryens — Valyria has hardly begun to rise yet with its dragons and the great empire that it built," he told EW back in November. "We're dealing with a different and older world and hopefully that will be part of the fun of the series."

HBO has said that the prequel will tell the origin story of the White Walkers, and will chronicle a devolution from a glorious to dark period in Westeros's history:

"The series chronicles the world’s descent from the golden Age of Heroes into its darkest hour. From the horrifying secrets of Westeros’s history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend, only one thing is for sure: It’s not the story we think we know."

It's widely rumoured that the show will hone in on the 'Children of the Forest' - the group of green beings who inhabited Westeros before humans turned up and eventually created the Night King to repel human advances.

What will it be called? 

Martin wrote on his blog a year ago that his vote for the title of the show would be The Long Night, however this was the name of season 8, episode 3 of Game of Thrones. He is an executive producer on the show, so will have a say, but he recently said he's "not supposed to call it The Long Night," so looks like he's been usurped. The current, widely cited 'working title' of the show is 'Bloodmoon'.

Who is the showrunner? What can we expect from her? 

English screenwriter Jane Goldman is the showrunner, and she also wrote the pilot.

She wrote the Colin Firth Kingsmen movies, as well as superhero satire cult classic Kick Ass (which all have a great sense of comic timing), she wrote the screenplay for horror classic The Woman In Black (so has a way with eerie tales) and penned two X-Men films (so knows fantasy/action tales too). She's also written the screenplay for the upcoming live-action adaptation of The Little Mermaid (she's been known in the past for her bold red hair).

She's got the thumbs up from Martin too: "she's a tremendous talent," he told EW. "She's going into territory that I haven't explored very much in the books. I've hinted about them, but she's a major writer, I love her work."

Fast fact: she's married to British comedian Jonathan Ross (power couple).

When will it hit our screens? 

While it's currently in production, HBO says that's just the pilot, and that the show will go through the normal production process, which means we can expect to wait at least a year until it's on our screens. At least.

What we do know is that the script and process has been in development for more than two years.

What other Game of Thrones projects can we expect? 

Martin said last year that there were five "successor shows" in discussion, but earlier this month he wrote an update on his blog, saying that only three shows from the fictional kingdoms are "moving along nicely". He did say he is loathed to call them "spin-offs".

Three of these, including 'Bloodmoon', are prequels, "set in different periods and featuring different characters and storylines".

One of the five storylines that has been shelved was led by Bryan Cogman, who was first hired as an assistant to GOT showrunners David Benioff and D B Weiss way before the series went to air. He then went on to be staff writer, then story editor, co-producer and supervising producer on the show.

Martin had said that Cogman is "the guy who knows the canon better than anyone", so we were very excited about his project. But, Cogman confirmed in April that his project had been shelved: he is now consulting on Amazon's Lord of the Rings series.

While Martin would not be pressed on what the plots of the still-in-development shows would focus around, he instructed fans to pick up a copy of Fire & Blood, which was released last year, and "come up with your own theories".

The book is a complete history of House Targaryen, set 300 years before the story of Game of Thrones, leading fans to speculate that one show will act as a prequel, exploring the family roots of Queen Daenerys.

Martin had said that we shouldn't expect to see all shows under development actually on TV, because, as he put it, "HBO is not about to become the Game of Thrones network." But, he did point out that there are enough plot lines to go on: "we do have an entire world and tens of thousands of years of history to play with".