Josh Brolin on playing Bush in biopic
Stars of Oliver Stone's latest film, W, have turned out in London's Leicester Square for its European premiere.
No Country for Old Men actor Josh Brolin plays US President George W Bush in the film chronicling his rise.
British actress Thandie Newton also appears as US Secretary of State Condoleezza Rice.
Stone said President Bush "had left us in a dark hole", but he wanted the film to help people understand more about the man himself.
The film is being shown in Leicester Square as part of the BFI 52nd London Film Festival.
W follows President Bush's ascent from his early days at Yale to the most powerful office in the world and the decision to go to war in Iraq.
Director Oliver Stone said George W Bush had 'changed history'
It also depicts his rise to power and struggle to escape the long shadow cast by his father, former President George Bush Snr.
Stone began filming W in May with the intention of rush-releasing it ahead of the US presidential election next month.
Speaking on the red carpet on Thursday night, the director said he supported Democratic presidential candidate Barack Obama, but insisted his film was not anti-Republican.
"It's a great story," he said. "This guy changed history. We underestimated him.
"He took over the world stage and pushed the extremists' buttons."
Stone, who has made previously made films about other presidents, revealed he thought W would be his "last one" on the subject.
"Kennedy and Nixon mark my youth very heavily and I think Bush is one of the most important figures of recent time."
Brolin, who also backed Mr Obama to be president, said he had initially turned down the part of the president.
"I didn't understand what he [Stone] was going for. I thought Oliver had an agenda," he said.
"It wasn't until I read the script that I realised it was a brilliant character study."
Josh Brolin stars as US President George W Bush
Newton said of her character: "I admire her discipline. What she has chosen to do with it I'm less in awe of."
She said she hoped the film would help people make decisions that "will be of benefit to the planet".
The cast also features Richard Dreyfuss as Dick Cheney, Ioan Gruffudd as Tony Blair and Jeffrey Wright as Colin Powell.
The film has received mixed reviews since its first screening in the US, but Brolin has received praise for his "arresting" work in the title role.
W will be released in the UK on 7 November.
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