Game of Thrones S07E05: Gilly revealed a HUGE Targaryen secret

The latest episode of Game of Thrones featured a revelation that dramatically changes existing lore within the world, and probably the course of the narrative to come.

Spoilers for Game of Thrones S07E05 follow.

In the latest episode, entitled Eastwatch, Gilly reads to Samwell from an old, forgotten historical record that reveals Prince Rhaegar had his marriage to Elia Martell annulled before secretly marrying another woman.

Connect the dots and that woman is Lyanna Stark, the mother of Jon Snow - which makes him a trueborn Targaryen with a more legitimate claim to the throne than his auntie Daenerys (Rhaegar's sister, the Mother of Dragons, Breaker of Chains etc).

Being trueborn rather than a bastard changes things up considerably in the Game of Thrones universe.

There was a clue last season in Bran's flashbacks to the Tower of Joy, where Jon Snow's real mother was revealed. Ser Arthur Dayne and his fellow Kingsguard soldiers were at Lyanna's deathbed instead of protecting anyone else in the Targaryen family - we now know this is because her infant would be the rightful heir to the throne.

Also, the general lore around this is that Rhaegar kidnapped Lyanna and raped her. That incited Robert's Rebellion, which saw the Targaryen dynasty come to a violent end and triggered pretty much every event that's ever happened in Game of Thrones as we know it.

So those lines Gilly read out and Sam ignored were enormous - they fundamentally change the lore that the entire TV show and series of books are based on and could impact greatly on Jon and Daenerys in the future.

The next episode of Game of Thrones airs in New Zealand on Monday, August 21.