Season five saw the television show move out of sync with the books, bringing key events forward such as Tyrion meeting Daenerys.
Game of Thrones blog Winter is Coming shared an excerpt from an upcoming book Tinderbox: HBO’s Ruthless Pursuit of New Frontiers, in which Martin relayed his fears about the direction the show was heading via his representative, Paul Haas.
Haas told the publication: “George loves Dan [Weiss] and Dave [Benioff], but after season five, he did start to worry about the path they were [going down] because George knows where the story goes.
“He started saying, ‘You’re not following my template’. The first 5 seasons stuck to George’s roadmap. Then they went off George’s roadmap.”
The 10-episode series will air at an unspecified date in 2022 on HBO Max. It is set 300 years before the timeline of Game of Thrones and follows the House Targaryen up to a bloody civil war called the Dance Of Dragons, which threatens to end the Targaryen reign.
The series is based on Martin’s novel Fire & Blood, published in 2018.
The show is one of six spin-offs currently in the works and includes Matt Smith, Olivia Cooke, Paddy Considine and Rhys Ifans among its cast.
Last month, the show expanded its ensemble with seven new cast members. Ryan Corr, Jefferson Hall (Vikings, Devs), David Horovitch, Graham McTavish (The Witcher, Outlander), Matthew Needham, Bill Paterson (Fleabag), and Gavin Spokes all boarded the series in roles that span different houses and lands familiar to the original Game Of Thrones show.