Though her first feature film, released in 1992, was terrific, it took another 25 years for Lili Fini Zanuck to direct her second.
The reason, explains the 63-year-old Oscar winner (as producer, with her late husband Richard Zanuck, of Driving Miss Daisy), was "freshman panic".
"After Rush I was offered lots of things and I thought 'that's not good enough, that's not good enough', until nobody cared any more," she says.
What sort of things did you turn down? "Jesus, do I want to bring back those ghosts? Primal Fear [the film that broke Edward Norton]. I turned that down three times. Se7en, with Denzel Washington [in the Morgan Freeman role] and Johnny Depp [in the role Brad Pitt would play in David Fincher's film]. There's just too many and none of it makes any sense."
It wasn't all bad, though. She was happily married to her producer husband - son of Twentieth Century Fox co-founder Daryl F. Zanuck - and got to spend lots of time with him before his death five years ago. "The truth is I'm not regretful," she says. "But when I'm directing I love it so much that it's beyond my belief that I could have gone without it for so long."
Her debut Rush was a gritty drama about two undercover cops (Jason Patric and Jennifer Jason Leigh) trying to bust a drug ring but getting hooked instead. Eric Clapton: A Life in 12 Bars is a documentary. They're miles apart, except they're not: both have soundtracks by the legendary English guitarist and both are about addiction.
Her new film came about, she says, because someone approached Clapton with the idea and he thought if someone was going to do it, it might as well be someone he trusted.
Though they were friends, Zanuck says: "We'd never had conversations of the depth we have in this. You don't know anybody this well."
She recorded conversations with her subject - about his troubled childhood (he was abandoned by his mother and raised by his grandmother), his failed relationships, his addictions to cocaine and alcohol - without a camera present; she felt it was less intimidating that way, more likely to elicit an honest and thoughtful response. And besides, she didn't want the audience to be distracted by the disconnect between what the people in the story look like now and the way they looked when the events they talk about were happening.
She cites the example of Pattie Boyd, a central figure in the drama and a source of many of the key images ("Nobody took selfies in those days," Zanuck says, "so thank God for Pattie and her camera"). A model in the swinging '60s, Boyd was married to George Harrison, Clapton's neighbour and friend. Clapton fell in love with her, tried his best to woo her, wrote the song Layla for and about her. Eventually he got his way. Though Boyd at 72 is "still beautiful", Zanuck says, "I don't know that she's beautiful in a way the audience would understand somebody being thunderstruck".
Not shooting her subjects in the present day meant Zanuck was dependent on archival material (all she shot, she says, is drone footage, mostly of Clapton's massive country pile Hurtwood Edge). And that put her at the mercy of a multitude of forces.
"It was my first documentary so I didn't know how much prayer was involved," she says. She'd track down someone who had a photo from a key moment in the story, she'd call them, and then "there's this moment of, like, 'I'll take a million'," she laughs. "You've got the maths wrong on this. We don't need the picture that badly."
Some of the material came from Clapton's archives, though he didn't really know what he had. "He wasn't exactly scrapbooking," she says.
There's a remarkable piece of footage in the documentary of Clapton inhaling cocaine from a knife, his nose a bleeding mess. It comes from Rolling Hotel, a tour film shot on a train but never released (for fairly obvious reasons). Clapton had no recollection of it, but like everything else in the film, he had no issues with her using the footage.
So, has he seen the finished film? And if so, how does he feel about it?
"I showed him an hour when it was done and he was so impressed," she says. "But later when I showed him the whole thing, I think there were things in it that were so arresting he didn't catch the next five things.
"I think he would get stuck on something that was very emotional. It is very hard to watch your life presented in this way."
Eric Clapton: A Life in 12 Bars screens at the British Film Festival. Details: britishfilmfestival.com.au