Game of Thrones star Kit Harington on Jon Snow's brutal decision in episode 3: "It didn’t sit well”

Jon Snow undergoes a "big change" in this week's Game of Thrones episode when the newly appointed Lord Commander of the Night's Watch has his authority tested.

In episode three, which aired in America last night and simultaneously in the UK in the early hours of this morning, Jon is seen ordering Janos Slynt to take charge of Greyguard, an abandoned castle on The Wall. When Slynt refuses to follow orders a number of times, Jon takes him out into the Castle Black courtyard and beheads him, as the rest of the Night's Watch – and Stannis – look on.

"There’s a great juxtaposition there from when Jon’s captured Ygritte and he knows he should kill her but he can’t do it because he’s too good of a person,” Harington says. "He had that moment again here. He’s thinking: ‘Can I kill a man in cold blood?’ And this time he does it. That’s a big change for Jon."

The execution was a tough scene to watch, and a difficult scene for Harington to film. The 28-year-old star admitted the turn of events "didn't sit well" with him, especially in light of the ISIS beheadings that were front-page news when he was filming.

“It felt really dark because of the current news, what was going on at the time. And I’m doing it on camera. It didn’t sit well," Harington told Entertainment Weekly.

"You can’t shy away from horror in drama and the things that you see on the news ever day,” he added. “But to have Jon doing it – whatever the right or wrong reasons he’s doing it – this is a character I love, and to have him committing this murder in cold blood, that for me was the most controversial bit this season.”

Game of Thrones continues tonight at 9pm on Sky Atlantic

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