They collaborated on the current release "The Ghost Writer," a mystery about a young author hired to pen a former British prime minister's memoir at an oceanfront house during winter. Williams plays the ex-official's wife.
Asked why she accepted the role, Williams listed the reasons as: "Roman Polanski and a wonderful part for an older woman and no pressure to be alluring or young or sexy, and a meaty subtext to work with."
"It far exceeded (my expectations) and continues to," the 41-year-old actress told UPI in New York recently. "The experience was extraordinary for so many reasons -- to work with Roman, to work with Ewan (McGregor) and Pierce (Brosnan) and Kim (Cattrall) and in those most extraordinary circumstances ... .That landscape on the first day that we did all the water scenes on the beach, Roman was saying: 'We're not ambling. This isn't a lovely, country walk. I want you to really march over these sand dunes.' And that's tiring. My legs were aching and we were walking faster and faster and Roman was sort of running backwards up the sand dunes and seemed never to tire. So, it exceeded all the expectations of the act of making the film and then to watch it and see what Roman had done with the raw material he had created was quite extraordinary."
Polanski, the Oscar-winning director of "The Pianist," reportedly completed "The Ghost Writer" after his September 2009 arrest and while imprisoned in Switzerland on an outstanding U.S. arrest warrant. The 76-year-old filmmaker is now under house arrest at his Swiss chalet while he awaits a decision on whether he will be extradited to Los Angeles in a 1977 case in which he was accused of drugging and raping a 13-year-old girl. Polanski, who had been living in France but was in Switzerland to attend a film festival at the time of his arrest, has not traveled to the United States since he pleaded guilty in a Los Angeles court decades ago to having unlawful sex with a minor, then fled the country before he could be sentenced.
Without specifically addressing Polanski's incarceration and what led to it, Williams said she was surprised to see what a dark, moody picture the director made once he was alone with the "The Ghost Writer" footage they had shot.
"I remember quite happy days on set, and mucking about with Ewan and Pierce, and we were cursed with good weather for a lot of the time," the actress said with a laugh. "And then to see this bleak, miserable film, it really is unsettling. It reminds me every time I watch it what a master Roman is of his oeuvre."
Williams said, however, that Polanski was such a perfectionist and so focused on the shots he wanted that he was sometimes harsh with his actors.
"If he's pre-occupied, your feelings and good manners and everything else goes out the window," she recalled.
"(But) it's like any great teacher; you're in awe of them," she said. "You want to gain their approval and if their approval is hard-won, then how much more valuable is it? When I got a, 'Great! Great!' I was like, 'Thank you!' … If everything's easy, then it's less rewarding. It was rewarding because it was terrifying."
Celebrity Families of 2014 [PHOTOS]