"They're yet to set a date, but told friends and family last week that they've got engaged", a source told the paper.
Their characters were love interests on the show in earlier seasons and after dating for quite some time, they made their first official appearance at the Olivier Awards in April 2016. "The engagement is announced between Kit, younger son of David and Deborah Harington of Worcestershire, and Rose, middle daughter of Sebastian and Candy Leslie of Aberdeenshire", it read.
Leslie was killed off in heartbreaking scenes in season four, but her relationship with Harington remained strong in the real world.
Instead of announcing it through a representative or on social media (Leslie has a Facebook page but Harington isn't really on it), the couple used the print edition of the Times-similarly to how fellow British actor Benedict Cumberbatch announced his own engagement in 2014.
Weddings on the show have historically not been successful; from the infamous Red Wedding to the marriage of Sansa Stark to villainous Ramsey Bolton. After the news of them buying a £1.75 million worth house together surfaced, it was obvious Kit would propose eventually.
Harington and Leslie have traditionally remained private about their courtship, though this summer, he told James Corden that he and Leslie moved in together.
Well, it sounds like that big step has finally happened, and it's no wonder why.
"No, I just think it's kind of nice - if you're going to live together, maybe to at least get engaged", Kidman said.
"It's as much her relationship as it is mine and I can't speak for both of us", he added.
Since the formalization, Kit Harington heaps praise on his partner.
"It's what I would have done if I wasn't famous".