Like Harry Potter before it, Game of Thrones has captured the imagination of a generation, and now the two blockbusting franchises are sharing more than just a common fanbase. Jim Broadbent – AKA Harry Potter's Professor Horace Slughorn – made his debut in the season 7 premiere of the HBO show, and many fans spotted a bizarre similarity between his two roles.

*Spoilers for Game of Thrones Season 7 to follow*

In the new season, Broadbent plays an archmaester who warns Samwell Tarly against entering a "restricted area" of the Citadel library. 

But here's where it gets interesting: there is also a restricted area of the library in Hogwarts. It's where Harry and Hermione – and at an earlier stage, a young Lord Voldemort – seek out information about horcruxes. And, as many fans have pointed out on social media, it's Broadbent's Professor Slughorn who the young Dark Lord goes to for information when he can't find what he is looking for in the restricted section – which represents a pleasingly specific overlap for the two franchises. 

Sam, like Riddle and Harry before him, ends up finding a way to sneak into the library, despite the protests of Broadbent's character. Hopefully this one doesn't go as badly south for him as it did for Professor Slughorn, who inadvertently assisted the evil wizard in becoming immortal by schooling him in the creation of horcruxes. 

Is it all a coincidence, or have the writing staff at the HBO show been mining JK Rowling's works for inspiration? To us, this sounds very much like mischief stage-managed...

Game of Thrones season 7 is on at 9pm on Monday 17th July on Sky Atlantic and NOW TV