Sienna Miller, 42, gives a rare insight into motherhood

Sienna Miller gave a very rare insight into motherhood as she discussed her daughter being ‘very critical’ about her fashion choices. 

The actress, 42, welcomed her second child – and first with Oli Green- in January, and also shares 11-year-old daughter Marlowe with ex-partner Tom Sturridge.

Sienna opened up about family life during a candid interview with The Guardian, following a ‘rough baby night’ with her youngest daughter.

She explained that the 10-year age gap between her daughters is, ‘actually quite useful because one is tiny and portable, and the other is becoming increasingly independent.’

Speaking about Marlowe, who walked the Cannes red carpet with her mother earlier this month, Sienna said: ‘She’s so stylish and very critical.’

‘She’s like a young Anna Wintour in her total disdain for some of the things I wear. In New York she thought I was mortifying. She wished I would brush my hair.’

It comes as Sienna revealed she has helped design a 33-piece summer capsule collection with Marks & Spencer’s.

On the collaboration, Sienna said: ‘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. 

‘Seeing the reaction to the Autumn campaign that I fronted, was phenomenal. To collaborate on a womenswear design project made total sense. I can’t wait to see what customers think of the collection.’

Her collection will launch at M&S.com and in 30 stores on Thursday June 6.

Sienna is thriving in motherhood as she stole the show on the red carpet in Cannes last week.

She was promoting her new movie – Kevin Costner ‘s western epic, Horizon: An American Saga.

Her co-star summed her up by saying: ‘Her outward beauty is undeniable, but she’s so skilled as an actress.’

Embracing being a mother again in her early forties , Sienna is undergoing a renaissance with fans and commentators declaring that the British actress has ‘never looked better’ despite the demands of work and having a young family.

Brand and Culture Expert Nick Ede told MailOnline that he predicts that Sienna could be about to ‘steal the crown to become the UKs biggest Hollywood star’.

He said: ‘Sienna’s been looking after herself and got herself red carpet ready knowing this is going to be her big return to the big screen and knowing all eyes will be on her. She’s done everything right and she commands The Croisette’ – the beating heart of Cannes.

Sienna’s breakthrough roles came 20 years ago in Layer Cake and Alfie – but despite winning plaudits for American Sniper her acting career hasn’t consistently hit the same heights.

But the she is back in the big time despite the demands of a red carpet promotional campaign in the south of France this week, Sienna has also brought her newborn baby and 11-year-daughter with her.

Sienna looks to have barely aged a day since breakthrough year of 2004. She has put her health and fitness down to regular yoga and a love of protein-rich fried eggs and vitamin-laden Marmite – ignoring trends like ‘chia seed and whatever grains’, Sienna said recently.

But she has confessed to ‘cheating’ by using a little fake tan to make her skin glow, her youthful appearance is down to regular facials starting at £400 for 90 minutes and her famous champagne blonde hair highlights will cost at least £500.

Experts are predicting that 2024 is the year she is stepping out of the shadows having been eclipsed for years by boyfriends such as Jude Law and Orlando Bloom as well as rumoured lovers Leonardo DiCaprio, Daniel Craig and Brad Pitt.

More Hollywood roles in her forties and a run on Broadway in New York, where she lives with her family, is also being predicted.

Nick Ede said that years of being ‘bypassed’ by directors for actresses on shows like The Crown and Downton Abbey may be over.

He said: ‘She has always been someone that has perhaps been more associated with her partners than her work but for once and for all she’s back and stealing the crown to become the UKs biggest Hollywood star.

‘Ms Millar is back at the top of her game and wowing the crowds in Cannes with her stylist clothes, fabulous looks and wonderful acting in the new Kevin Costner movie Horizon.

‘Sienna has always been a brilliant actress but it feels that for a while she was being bypassed by UK stars who appeared in The Crown and people were not considering Sienna as one of our best actresses.

‘With this new movie and her post baby glow she has the world at her feet and with the great reviews she’s receiving I think she will be up for awards and be offered some meaty starring roles in the next few years.

‘I can see her getting some big brand endorsements too and she’s always loved treading the boards so I wouldn’t be surprised if she decided to do a play on Broadway for a limited run to build her fanbase and her acting resume just gets better and better’.