According to the news, who is Sienna Miller?

One of the world’s biggest media groups, News International, is apologizing and offering compensation for the actions of one of its newspapers which hacked into the mobile phones of celebrities over a sustained period. Here is Gabriel Gatehouse.
    These are sensational admissions that are likely to cost the newspaper tens of millions of dollars in compensation payments. The list of claimants includes film stars, like the actress Sienna Miller and public figures such as the politician and former Culture Minister Tessa Jowell. A reporter and a private investigator at News of the World had already been jailed in 2007 for hacking into voicemail messages left on mobile telephones. But the News of the World had always claimed that instances of hacking were isolated and that the pair acted without the knowledge of senior editors. It now appears the problem went far further.