Good news for those who are already preparing to go into mourning as the end of an era is ushered in with the Game of Thrones finale. A new spin-off pilot series has been ordered by HBO which is set thousands of years before the events of the main series.

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It's official: Game of Thrones will not be the last we see of Westeros.

Network HBO has announced it is working on the pilot for a brand new series which is based thousands of years before the War of the Five Kings during a time known by the characters in GOT as the Age of Heroes, a period of history when near-mythical figures enjoyed all manner of unusual adventures.

The prequel which is in the early stages of production will, according to HBO, look back to "the world's descent from the golden Age of Heroes into its darkest hour. From the horrifying secrets of Westeros' history to the true origin of the White Walkers, the mysteries of the East to the Starks of legend, it's not the story we think we know."

There were five potential spin-offs brought to the table, but in the War of Five Prequels, only one could be victor.

George RR Martin, who wrote the original novels on which Game of Thrones was based, has revealed that fans will see a very different world to the one we have grown to know and love.

"Westeros is a very different place," he teased, "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. We're dealing with a different and older world and hopefully that will be part of the fun of the series."

So, what do we know about this new prequel?

1) There will be a wait until it arrives on screen: The very earliest we can expect to see the GOT prequel is 2020.

2) Who will be in it? A number of the cast have been revealed: they include John Simm, Naomi Watts (who will play "a socialite with a dark secret" and will lead the series, will she be Nissa Nissa, wife of ancient hero Azor Ahai?), Miranda Richardson and Jamie Campbell-Bower.

3) Anyone else? According to rumours, we can expect Marquis Rodriguez (Luke Cage), Poldark's Richard McCabe, John Heffernan (Collateral, Dracula), Josh Whitehouse (Poldark), Naomi Ackie (Star Wars Episode IX), Dixie Egerickx (Patrick Melrose), Ivanno Jeremiah (Humans, Doctor Who), Denise Gough (Angels in America), Sheila Atim (Harlots), Georgie Henley (Chronicles of Narnia), Alex Sharp (To the Bone) and Toby Regbo (Fantastic Beasts: The Crimes of Grindelwald).

4) Who will be writing the prequel? With help from George RR Martin himself, it'll be Jane Goldman, who was the screenwriter on Kick Ass and wrote the screenplay for Neil Gaiman and Susan Hill's The Woman in Black.

5) Tell me about the Age of Heroes: I'm glad you asked. It took place many millennia before the events of Game of Thrones and we will meet distant ancestors of many GOT characters and see the beginning of Westeros as we know it. We'll meet Lann the Clever, the first Lannister who found fame and fortune, Bran the builder, the Stark who created Winterfell and the Wall and the Grey King of the Iron Islands. And we will meet other legendary figures such as the blind knight Symeon Star-Eyes.

6) When was the Age of Heroes? It was around 10,000 years before Game of Thrones was set and ended around 6,000 years before the show started. In the episode Lord Snow, Old Nan told Brand stories while he recuperated from a fall: "Thousands of years ago, there came a night that lasted a generation. Kings froze to death in their castles, same as the shepherds in their huts; and women smothered their babies rather than see them starve, and wept, and felt the tears freeze on their cheeks... In that darkness the White Walkers came for the first time. They swept through cities and kingdoms, riding their dead horses, hunting with their packs of pale spiders big as hounds."

7) Is there a working title? There is: The Long Night. Or maybe Bloodmoon. Let's face it, we don't really know.

8) Will any characters return? Given that time scale, it seems unlikely. And it's even more unlikely when you hear that Martin has said: "None of the characters or actors from Game of Thrones will appear in the new show." But could they appear as their own ancestors…?

* The finale of Game of Thrones is on HBO on Sunday May 19 in America and at 2am on Monday May 20 in the UK, rerun on Sky Atlantic and Now TV at 9pm.