Carice Van Houten spent six hours in make-up ahead of 'Game of Thrones' shock twist.

Carice Van Houten

Carice Van Houten

Fans who tuned into the premiere of the HBO drama's sixth season were stunned to discover the 39-year-old actress' alter ego Melisandre, aka The Red Woman, is actually a frail old crone, and the Dutch star admits it took a lot of work for her to convincingly look so "ancient".

She said: "I did six hours of make-up. It's not just one face that they glue on you. But it's worth it because of what you look like after. It was quite nice, it was like a zen practice for me, I quite enjoyed it.

"I need music. I can't do it without. I have very eclectic taste, from jazz to reggae to indie rock, pop, a lot."

While Carice - who is expecting her first child with partner Guy Pearce - enjoyed having the make-up put on, she couldn't wait to shed her disguise once filming was over.

She added: "It's funny because you can sit there for six hours and it's fine but once it's over you just want to rip it off. Then, that hour to take it off, that's really long. You feel like, 'Just get it off me!' "

The actress estimates her character's actual age to be "200-300", and producers brought in an 80-year-old body double for when she was standing nude in front of a mirror after taking off her seemingly-magical choker.

Carice said of her double: "[She was] this lovely lady from Ireland. She was really sweet."

The reveal even came as a surprise to Carice's co-stars.

Isaac Hempstead Wright, who plays Bran Stark, recalled: "I was on set one day in my trailer, I could hear Carice outside.

"I could just hear her voice, so I went, 'Oh hi Carice,' so she opened the trailer door and I went, "Aaah! Oh! How are you doing?' It was very funny. It was really funny. It was so well done."