Rewind to May 2003 and Sienna Miller is everyone's favourite boho style icon.

She truly embraced the folksy, feminine look.

A boho style high-point thanks to this ethereal Alexander McQueen dress with silver flats at the Cold Mountain premiere in 2003.

She flirts with a brunette up 'do at the 2004 Oscars but this strapless Matthew Williamson gown with gold armcuffs encapsulates her signature bohemian aesthetic.

Fun fact: Sienna co-designed the emerald green and gold gown.

Another premiere, another arm cuff. She sports a very relaxed look to the London premiere of Layer Cake in 2004.

It's a double strapped Chloe gown for the Venice Film Festival in 2004.

She's accessorising this floaty McQueen gown with layers of beads and a scarf in 2005.

Now something of a Williamson muse, Sienna attends the designer's 2005 gala in one of his pink striped designs and showing off a new accessory - the gold hippy headband.

The actress goes for a breathtaking strapless Christian Dior gown, diamond choker and slightly ruffled up'do at the premiere of Casanova in 2005.

But boho is banished in favour of a sleek crop and sharp bustier and trousers combo at Casanova's LA premiere in 2005.

She's more modern rock than floaty boho in a glittery Burberry mini at the Met Gala in 2006.

Quintessential Sienna at the Factory Girl premiere in 2007.

She's truly back to her hippie roots with a medieval princess vibe in a white Marchesa fishtail gown and crown of braids for the 2007 Met Gala.

She embraces a risky red carpet outfit and thicker eyebrows (long before they became mainstream-trendy) to celebrate Valentino's 45 years in fashion in 2007.

There's no hint of that early years bohemian spirit in this vampy Christian Dior gown and sleek hair at the 2008 Baftas.

She adds a sharp edge to her black tasselled Jasmine de Milo dress with a vintage bowler hat at the Edge of Love premiere in 2008.

She's very much back to boho in a puffball All Saints dress in 2009.

Aaaand folk and frippery is banished a month later at the ShoWest awards where the actress showcases a distinctive geometric print mini dress by Jonathan Saunders.

She's in her own 2812 label emerald green sparkling mini for the 2009 MTV Movie Awards.

It's an old Hollywood glamour vibe in Yves Saint Laurent at the 2009 premiere of G.I. Joe: The Rise of Cobra.

At the 2009 premiere of The September Issue, Sienna braves a tiny Thakoon flared mini and shades to mingle with the high fashion set.

High drama with a rock chick edge in Emilio Pucci for the 2010 Met Gala.

Later that year she's back to her old faithful Matthew Williamson at the designer's book launch.

She cuts an Audrey Hepburn-esque figure in an LBD from her 2812 label in 2011.

She's understated and chic in a Hugo Boss gown, dressed up with bold gold accessories in 2012.

She's in a rebellios mood for the 2013 Golden Globes, wowing the red carpet in a floral Erdem crop top and matching floor-length skirt.

She's best known for boho, but we've get the feeling Sienna prefers outfits with a little more edge.

The actress dons a studded Burberry biker jacket and matching studded headband with white crepe dress for the punk-themed Met Gala last year.

Yes, that is pink hair. Her experimental approach to red carpet dressing takes a grungy turn in this divine emerald green Burberry gown at the British Fashion Awards.

She's in McQueen again for the 2014 Oscars and the gold armcuffs are back too, fiercer than ever.

She's giving Kate Moss a run for her money at the model's Topshop launch in April in a stunning silver metallic mesh dress.

Wearing a slicked back do at the premiere for Foxcatcher at The 52nd New York Film Festival in October this year, Sienna looked sensational in a midriff-baring top and metallic skirt.

Opting for elegant Erdem here, she attended the International Medical Corps Awards, Los Angeles in October and looked radiant with her new cropped bob.

At Mario Testino's 60th birthday party this October, the star turned up with her equally dapper boyfriend Tom Sturridge in tow. She opted for a red embroidered prom dress-style frock.

Perhaps one of our favourite looks, early December, while out and about in New York, Sienna finally shunned her old boho look and gone for clean separates in block colours, all by Miu Miu. The short tousled hair style has changed her look completely.

In an A.L.C dress at the American Sniper film luncheon, New York, in December. The ultimate sport luxe look done well.

Having starred in one of Burberry's campaigns, with her other half no less, Sienna opted to wear the British brand to November's Evening Standard Theatre Awards.

In Balenciaga at the American Sniper film premiere, New York in December. With her short hair, bold white dress, Sienna has completely changed her look of late, and we approve. 

At the 2015 Oscars in Oscar de la Renta.

Wearing a brilliantly bold one-shouldered dress by Marc Jacobs, to promote Burnt.

In plunging Rodarte to promote Burnt.

Owning the 2015 Cannes Film Festival in tiered Gucci.

Sienna wows in shimmering Ralph Lauren at the amfAR Gala during the 2015 Cannes Film Festival.

Stepping out again at Cannes in geometric Valentino.

In shimmering custom-made Burberry at the 2016 Met Gala.

Pairing a comfy knit with a pleated midi skirt to nail transitional style.