Sienna Miller Is Crowned Grazia’s Best Dressed Of 2015

2015 was the year that Sienna Miller sprang back onto our fashion radar (just call it a Sienn-aissance) and in this week's issue she is crowned Grazia's Best Dressed of the Year.

Her stylist Kate Young has steered Sienna through 12 months on the red carpet, from awards season to her high profile role as a juror at the Cannes Film Festival. From classic Lanvin to whimsical Valentino to chic Balenciaga, Sienna has been the chief red carpet dresser of the year.

Her stylist Kate has said of Sienna's style: 'With Sienna, I'm just thinking about good dresses, fun dresses - and there are a lot of red carpets, so it's really fun.'

'Her career changed in the last 18 months,' Kate adds. 'She's in really serious movies and doing an amazing job in them. I like to think the fashion relates to her career.' She adds: 'I think she has really good style and I'd love to take credit for it, but it's mostly her - she has great taste.'

At the Cannes Film Festival Sienna premiered creative director Julie de Libran's first Sonia Rykiel outing in a pre-fall custom made black velvet dress and cape scattered with stars. Julie de Lbran said to Grazia: 'Sienna takes risks and knows what suits her. You can tell she enjoys dresses that are feminine but with character. She brings a lot of personality in the way she puts together... she personalised this look with a stunning choker and braided hair, which was so unexpected and chic... she looked striking and felt confident.'

Then we come to the hair - Sienna's cut was a move that helped transform her into a movie star. Luke Hersheson, who has worked with her for eight years, said of the decision to cut off her hair: 'She was always quite a long-hair girl because she was such an icon for the whole boho thing. It was a massive deal for her to cut it; it was brave. But it was always the plan to cut it off at some point; to find the right moment and the right thing. You always need to change your trademark. It keeps you fresh and a trendsetter, when you're prepared to let go of what people think of as your "thing".'

Pick up this week's issue of Grazia to read more about how Sienna became red carpet royalty in 2015

See all of Sienna's best looks of the year in the gallery below...