With a signature style that is as admired as her on-screen executions, actor Sienna Miller is truly deserving of 'icon' titles in relation to both beauty and fashion.

In our July/August issue of Harper's Bazaar, out now, the 42-year-old talks fame, family and filming, but behind the scenes at her cover shoot we asked Miller to share how her beauty philosophy has evolved over her adult life. She reveals this – and "authentically" what's in her beauty bag, "complete with dirty smudges" – in the video, above.

sienna miller
Emma Summerton

While sharing her appreciation for professional make-up artistry (from prosthetics used to transform her into Beth Ailes for The Loudest Voice, to the brown contacts and heavy Sixties make-up donned playing Edie Sedgwick in Factory Girl), Miller describes her personal aesthetic as "natural".

sienna miller on the set of "factory girl"
James Devaney//Getty Images
Sienna Miller as Edie Sedgwick in Factory Girl

"I think since I became a young woman, I’ve always been more minimalist," she says, saying she feels her most beautiful when barefaced but "a little bit sun-kissed". To achieve her trademark glow, she's big on skincare and complexion products, from the "amazing" Sarah Chapman Vitamin C Power 1 Face Serum to the Pharma Développement A313 cream – the retinol her close friend Alexa Chung got her on to. "It’s described as 'the French girl secret to great skin'," she shares.

Sarah Chapman Vitamin C Power 1 Face Serum
Sarah Chapman Vitamin C Power 1 Face Serum
Pharma Développement A313
Pharma Développement A313
Now 34% Off
Glow Recipe Watermelon Glow Niacinamide Hue Drops
Glow Recipe Watermelon Glow Niacinamide Hue Drops
Charlotte Tilbury Hollywood Flawless Filter
Charlotte Tilbury Hollywood Flawless Filter

Meanwhile, it was her eldest daughter, 11-year-old Marlowe, who persuaded her to buy the Glow Recipe Watermelon Glow Niacinamide Hue Drops and Charlotte Tilbury Hollywood Flawless Filter. The latter, she says, does what it says on the tin – think "a glowy, dewy, perfect young face".

sienna miller
Emma Summerton

When it comes to ageing, Miller discusses her stance on cosmetic procedures. Serious facials are her thing, she says, citing London's Sarah Chapman, Shane Cooper and Keren Bartov as the pros she sees. "I think if you can do a little bit of laser and the right Morpheus8 – or whatever it is – if you can do those treatments as you get older you can avoid filler and Botox and things that I think really change people." She continues: "It’s nice to see people looking older and looking like themselves otherwise it can look like you’re wearing your insecurity and facing the world with that as opposed to celebrating the fact that it’s all going south."

Clearly she takes this preventative approach home with her, adding that she regularly uses the Lyma Laser while watching TV. "I think it really works," she says of the device.

The Lyma Laser Starter Kit

The Lyma Laser Starter Kit

Again, her tendency towards the natural can be seen via her usually tousled hair. "My signature hairstyle would be 'just rolled out of bed'," she jokes, explaining that her naturally wavy hair "looks better if I just let it dry and leave it".

While she will occasionally borrow Marlowe's Dyson AirWrap, Miller admits to being lazy, "– and because my whole thing is slightly undone I can get away with it," she says. The one thing she does swear by is the Hair by Sam McKnight Cool Girl spray, a texture mist which enhances her nonchalant chic.

When it comes to make-up, the talent swears by the Yves Saint Laurent Touche Éclat Illuminating Pen and Glossier Stretch Balm Concealer applied with the Pat McGrath Labs Skin Fetish: Sublime Perfection Concealer Brush, which clearly erases any evidence of sleepless nights spent with her five-month-old baby girl. (That plus, perhaps, The Outset Smoothing Vitamin C Eye + Expression Lines Cream which she also retrieves from her "bulging" beauty bag.)

Yves Saint Laurent Touche Éclat Illuminating Pen
Yves Saint Laurent Touche Éclat Illuminating Pen
Glossier Stretch Concealer
Glossier Stretch Concealer
Pat McGrath Labs Fetish Sublime Perfection Concealer Brush
Pat McGrath Labs Fetish Sublime Perfection Concealer Brush
 The Outset Smoothing Vitamin C Eye + Expression Lines Cream
The Outset Smoothing Vitamin C Eye + Expression Lines Cream
Now 12% Off

Miller too reveals her favourite perfumes as the E11even Fragrance Oil and Le Labo Thé Noir 29; her go-to lip products being the Summer Fridays Lip Butter Balm and Westman Atelier Lip Suede: Les Nudes; her love of the MV Rose Hydrating Mist and Macrene Actives High Performance Face Cream – and so much more. Watch the full interview in the video, above.

sienna miller
Emma Summerton