Richard talks about Mischa in a interview

Mischa was a bolt from the blue,” he recalls. When I started getting into the production, my granddaughter Alice was recovering from injuries sustained in the tsunami disaster of 2004. Her legs were in bad shape, but she’s fine now. My wife Sheila and I were visiting her regularly in hospital, and on one occasion I was telling her about the casting of the movie. I was telling her about Shirley Maclaine, Christopher Plummer and so on, but when I mentioned Mischa Barton she went, ‘Mischa Barton! You haven’t got Mischa Barton!’ And she forgot Shirley Maclaine and everyone else. She leant over and under her bed she pulled out two magazines, on the front of which were Mischa Barton. I realised then we’d cast a very hot commodity.”

Source: I want to die on a movie set - icWales