After starring together in 2018's Winchester, the two are now portraying royal lovers Catherine the Great and Grigory Potemkin, respectively, in HBO's new Catherine the Great series. ET spoke with Mirren and Clarke at the Los Angeles premiere for the show on Thursday, where they opened up about how they got through filming a number of steamy sex scenes together.
Mirren joked to ET's Lauren Zima that she actually had "a lot of scenes with a lot of beautiful guys" while playing Catherine, the Russian empress who was known for having many lovers throughout her reign from 1762 to 1796. But just as Grigory was one of Catherine's "favorites" back in the day, it seems Clarke was also a favorite co-star for the 74-year-old actress.
"What a beautiful guy to have those sorts of scenes with," Mirren said of Clarke. "Jason is the most wonderful actor to work with. He's this great combination of very masculine but at the same time very generous and it's a lovely combination."
"I'd work with him again and again," she added. "I've only done it twice so far. We are [close], we love each other."
Clarke expressed similar sentiments about Mirren, telling ET that the two had "a lot of fun" on set together, even when it came time to film the more intimate scenes.
"Helen is very naughty, very cheeky, she's very alive and mischevious, so it's easy," he explained. "The funny thing is, you're sitting there with Helen and you watch her in a close-up and then bang! You're like, it's quite stunning what she does."
"She's always cheeky," he added. "We always laugh. We were being mischevious in some of the great palaces of Europe."
Clarke teased that some of the steamy scenes that fans will get to see in Catherine the Great will include everything from "steambaths" to "horses," as it was rumored that the Russian ruler was also intimate with animals, specifically horses.
"Catherine and Potemkin, they were wonderful partners," he explained. "It's a great relationship ... they were an amazing couple."
Dame Mirren is certainly no stranger to bringing royal rulers to life. She's portrayed everyone from Queen Charlotte in The Madness of King George (1994) to Queen Elizabeth II in The Audience (2013) and The Queen (2006) to Elizabeth I in a TV miniseries.
She told ET that playing this powerful new role of Catherine, a woman who wouldn't let anyone stand in her way, was "an amazing challenge."
"It was hard work, and very concentrated work," she recalled. "But also fun because there were beautiful costumes, beautiful sets. I had a director, Philip [Martin], who kept me laughing all day long. And my co-star, Jason, who was so extraordinary and also kept me laughing all day long."
Catherine the Great debuts Oct. 21 on HBO. In the meantime, hear more on Mirren in the video below!