Dillane returns ?

In these days they’re shooting for the eighth season of Game of Thrones.
From the leaked photos we can see Winterfell besieged by strangers and lapped by the flames.
But what caught the attention is the actor Stephen Dillane, who has been photographed on the set more than once.
In a photo, he even seems to wear stage costume.
Simply a flashback or the return of Stannis Baratheon?
Stephen Dillane in the past has repeatedly stressed how he hated the role he interpreted. Did the scent of money change his mind?
The Hollywood Reporter indicates how likely date to end shooting August 2018, Game of Thrones 8 will arrive on TV no earlier than 2019.