The actors starred alongside each other in 2004's epic war film Troy, and Diane admits the veteran ruined what should have been a thrilling movie experience with his bad attitude.

"It kind of sucked," she told her Sky co-star Norman Reedus in a Buzzfeed interview. "He’s dead, so I can say that. But he wasn’t the most pleasant person."

The Irish actor passed away at the age of 81 in December, 2013, but Diane revealed the whole Troy cast had been worried the star would drop dead before filming was over.

"He could barely make it up the stairs," she continued. "We were on a set that was... you know, you have to climb, like, I don’t know, 100 steps to go up. He was just... first of all, everybody thought he was gonna die right there and then. Because it was, you know, 120 degrees, and he had to walk up 100 stairs. And he was very old, and very drunk!"

The 39-year-old's biggest problem with Peter, who was nominated for seven Academy Awards during his career but failed to win any, was his ego.

While she acknowledges the star had produced some great work in movies including Lawrence of Arabia, The Stunt Man and Venus, Diane didn't appreciate the way he carried himself on set.

"He was just a drunk," she said. "You know, he had a two-day part, and I played Helen of Troy and he was Peter O’Toole, and he just wanted to make sure that everybody knew that he was Peter O’Toole."