The Harry Potter actor announced his involvement in the series back in August 2016, but little detail was shared other than the fact that his role was a “significant” one. Earlier this year, he revealed that he will play “an old professor character”. “I’m a maester, an archmaester,” Broadbent told Screencrush, and revealed that he appears in five of the seven episodes. “I did sort of one major scene in each episode,” he explained.

Since his casting was announced, fans of the Game of Thrones books have speculated that Broadbent might be playing Maester Marwyn, an archmaester of the Citadel. Marwyn the Mage, as he is also known, is a maverick scholar who spent many years travelling the Seven Kingdoms to learn about magic and anatomy. In Martin’s fourth novel, A Feast For Crows, he meets with Samwell Tarley who tells him about his travels and his encounter with the White Walkers. HOW TO WATCH GAME OF THRONES SEASON 7 ONLINE FOR FREE

GETTY Jim Broadbent is joining the cast of Game of Thrones season 7

GETTY Broadbent is best-known for playing Professor Slughorn in Harry Potter

The old maester immediately announces that he is off to meet Daenerys Targaryen, and orders Sam to keep quiet about the Queen and her dragons, finish his studies and return to the Wall as quickly as possible. In the season six finale, Sam arrived at the Citadel and was sent to the library to wait for an archmaester. Broadbent has confirmed that he filmed most of his scenes with John Bradley, who plays Sam, giving the biggest hint yet that he will be playing Marwyn. But what purpose his character will serve is as yet unknown. WHAT TIME DOES GAME OF THRONES SEASON 7 START?

HBO Samwell Tarley arrived at the Citadel in the Game of Thrones season six finale