It’s no secret that Sienna Miller is a major style muse in the Red office.

The queen of nonchalant cool, Sienna is up there with Kate Moss when it comes to renowned British fashion exports and there’s pretty much nothing we wouldn’t do for thirty seconds inside her wardrobe.

The definition of a 21st-century It-girl, if we had to sum up Sienna’s style in three words, they’d be polished, boho, cool. Whether she’s strolling around NYC in denim cut-offs and a khaki utility jacket or rolling up to Met Gala afterparties in a ruffled blouse and jeans, Sienna always looks effortlessly put together.

Team Red’s forever inspiration when it comes to capsule wardrobe buys, Sienna’s style has been at the front of our mind this week as the temperature ramped up and we’ve been shopping for wear-on-repeat summer staples.

Our first port of call? Marks and Spencer, of course. A favourite of Sienna’s too (the A-lister teamed up with the brand for a killer collection back in 2024), M&S has established itself as the high street’s ultimate style destination in recent years and repeat readers will know we love an M&S piece or two (fine, make that ten).

Inspired by our love for both British icons, below you’ll find the five Sienna Miller-inspired pieces we’re snapping up this week at M&S. We’re sure she’d approve.

M&S, Pure Cotton Ruffle Embroidered Blouse, £36.00 SHOP NOW

No one loves a ruffled blouse more than Sienna – especially paired with denim.

M&S, Denim High Waisted Jorts with Linen, £30.00 SHOP NOW

Speaking of denim, cut-offs are another surefire Sienna staple. That said, the bum-grazing style she tends to wear most often isn’t for everyone, so we’ve settled on this flattering, longer style.

M&S, Satin V-Neck Lace Insert Midi Slip Dress, £50.00 SHOP NOW

Lace-trimmed slip dresses are another Sienna favourite and this M&S style looks so much more expensive than it is. Win, win.

Whistles via M&S, Mia Cotton Blend Utility Jacket, £99.00 SHOP NOW

Sienna’s been seen out and about in khaki jackets on numerous occasions and we love the structured collar on this particular cotton-blend military jacket.

M&S, Linen Rich Drawstring Wide Leg Trousers, £28.00 SHOP NOW

Linen and heatwaves go hand-in-hand, but what sets this pair apart from the rest are those cool-girl stripes (back in 2023, Sienna wore a similar pair to Wimbledon and we’ve wanted some ever since).