Unrecognisable: Sienna Miller shows off her new RED tresses at sister's collection launch
DESPITE it being her sister Savannah's big night, it was Sienna Miller's tresses that stole the limelight in London yesterday evening.
Sienna Miller looked remarkably different in London last night
Gone were the British beauty's iconic blonde locks in favour of a bright red look, as she cosied up to her sibling at the launch party for Nine By Savannah Miller.
The actress beamed with pride while posing with her sister, after showing off her transformation on arrival at the Debenhams bash.
Wearing her hair down in a natural wave, the newly-single 33-year-old kept the rest of her ensemble very low-key.
Hiding her slim frame under a loose-fitting grey top, Sienna also chose a black pair of skinnies and suede heels.
The actress unveiled her new 'do at the Nine By Savannah Miller launch
Sienna has decided to dye her blonde hair, red
The Alfie star appeared to be wearing very little make-up, before adding a fluffy brown coat and bold yellow tote to her outfit as she left.
It is thought Sienna's fresh 'do is for her role in The Lost City of Z, which she has been busy shooting in Northern Ireland recently.
The flick, based on David Grann's 2009 novel, follows the story of British explorer Percy Fawcett and also stars Charlie Hunnam and Robert Pattinson.
The star was much more casually dressed than her blonde sibling
Sienna Miller and Jimmy Reminisce About Filming Factory Girl
Savannah meanwhile - who is three years older than her famous family member - looked much more glamourous in a sequinned LBD, leather jacket and eye-catching heels.
Speaking about her turbulent year in the October issue of British Vogue, Sienna - who split from Tom Sturridge this summer - said: "Everything's shifting. It's actually been the s*******t year, and amazing.
"It's always yin and yang. I feel like if you're excelling in one area, it's hard to manage both and I do feel like the work is going really well."
Sienna later added a fluffy brown coat to her attire