The 70-year-old actress shares on an interview with ET her surprising secret to her 18 years of marriage with husband Taylor Hackford, Wednesday, Feb. 3 and shares good moments with Actor Allan Rickman before he died.

After 30 years of being together, Mirren and Hackford had always kept the fire of love burning, though sometimes their work makes them apart from each other, they always make time to make it work.

"Spending a lot of time apart," Mirren told ET with a laugh. “We missed each other terribly…”

According to Entertainment Tonight, the actress reveals that she and Hackford -- who tied the knot in 1997 -- do "miss each other terribly" when they are away, but added that it's important they give each other "room to be who they want to be," as well as supporting one another in their professional and personal lives.

"That has to be a two-way street," she added. "I'm very lucky that Taylor gives the same to me, you know? It's a mutually-supportive relationship."

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The English actress, who was promoting her new movie, Eye in the Sky, a thriller which centers around the controversy of drone warfare, also hat while she usually chooses projects based on the character she will play, in this case, it was the story that attracted her.

"The greater appeal was the totality of the film, the totality of the story, and the way in which it brings up all the complicated moral issues of war, and presents it, I think, in an extremely dramatic and truthful way," she said. "I wanted to do the character the best I could to fulfill its function in the story, but really it was the story that I thought was really interesting."

The Woman in Gold actress explained to ET that she hopes the film will leave viewers thinking about the moral implications of unmanned combat.

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"In a way, it's sort of like a courtroom drama," she said. " We're presenting the evidence of a particular action, and it's being done in your name, you sitting out there in the audience. Do you think this is the right thing, or do you not?"

Eye in the Sky was also one of Alan Rickman's final projects and, according to ET, audiences in the screening reacted audibly when the late British actor--who died on Jan. 14 after a battle with cancer--appeared onscreen.

"He was the best person to go out to dinner with," Mirren recalled when asked about Rickman. "He was very generous. He always insisted on paying the bill, he was just entertaining and fun and funny and loved going out to dinner and chatting. He loved that."

Eye in the Sky hits theaters March 11.

Tags: helen mirren Alan Rickman Taylor Hackford