Sienna Miller has designed the ultimate boho-chic…

Sienna Miller has designed the ultimate boho-chic summer clothing collection for M&S

As Kate Moss did for Topshop, Sienna Miller will now do for M&S.

The British actress announced she has helped design a 33-piece summer capsule collection which takes its cues from her own wardrobe. No prizes for guessing, then, it is a treasure trove of boho-chic which might well have strutted out of Glastonbury circa 2004.

Yes, that means coin belts (£29.50), block-printed quilt jackets (£65), matching sarongs (£25) and beaded, floaty white vest tops (£49.50) all make for headline acts. It comes after Miller became the face of the British retailer’s autumn winter campaign last year and follows Alexa Chung’s footsteps, who also designed a successful range for M&S in 2016.

“We designed this a year ago before this whole resurgence of the kind of clothes that I love to wear,” she said, during a press launch on Tuesday. “It's really timed out perfectly that [boho] happens to be trendy now, but I think this is what I would have done irrespective of that.”

She worked with M&S to make “things to feel very antique and thin” (which was “a compromise”, as the retailer has thickness standards to allow for wear, “but I won,” she quipped). “I think people are beautiful in floaty things – so I'm happy boho is back. I just can't believe it's now vintage. That makes me feel old.”

In December, Miller gave birth to her second child, and first with boyfriend Oli Green. But she has made sure to make a mark on 2024’s biggest red carpets nonetheless. Appearing at the Met Gala and the Cannes Film Festival, Miller doubled down on her love of all things flimsy and fluttering. On both occasions she opted for Chloé gowns, the Parisian house which has recently turned back to bohemia thanks to new creative director Chemena Kamali.

Kamali’s silk mousseline, ruffled Chloé frocks might set you back £3,900, but Miller has created similar designs – in baby blue and ivory cotton – for just £89. It’s “Sienna’s ‘dress of the season” reads a statement from the brand. “Without doubt the hero of the entire collection.” Completing this summer Sienna-drobe are metallic, thong sandals (£49.50), a trusty pair of baggy, blue jeans (£49.50), various, simple swimsuits and Ibiza-ready cowboy boot mules (£65). “I have always had a genuine love for M&S — it's a brand that is part of the fabric of British life and holds special associations for so many people,” says Miller. “To collaborate on a womenswear design project made total sense. I can’t wait to see what customers think.”

The partnership is another example of the M&S boom, as the company goes from economic strength to strength. It reported it was in the “strongest financial health since 1997”, announcing pre-tax profits of £716mn for the year to March 30 (up from £453mn in 2022). It’s solid clothing division is in part to thank.

Sparks bosses will hope Miller, catnip for the Nineties / Noughties crowd and now — having enjoyed her recent Siennaissance — Gen Z too, will only contribute to this buzz. Set your alarms — if it is to go down Moss and Topshop style, those who succeed will be selling pieces for profit within the decade.