At least hippie Sienna hasn't burnt her bra

The star's plunging cheesecloth dress revealed more than expected while filming Hippie Hippie Shake in London's Notting Hill.

Her lacy lingerie was clearly visible as she waltzed along Portobello Road totting a large suitcase.

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Sienna is starring as Louise Ferrier, the girlfriend of Richard Neville, the editor of notorious counterculture magazine Oz.

She recently said the Swinging Sixties have always held a strong appeal, telling the Telegraph: "I ache with a nostalgia for a decade I never knew."

"I've always loved the 1960s – how proactive young people were then. Our generation is so coloured by the internet and by celebrity culture."

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"What they were doing in the 1960s came out of an innocence that we've lost. No one knew things weren't possible then; everybody could be absolutely themselves, and Oz magazine was about that generation's right to speak freely."

Next up, Sienna is set to star in A Woman of No Importance, a comedy co-starring Annette Bening.

The 25-year-old, who has been keeping close company with Rhys Ifans in recent months, is planning to eventually step away from the spotlight, albeit briefly.

She has said: "I'm knackered. I need a break."