Sienna Miller cuts a casual figure in mustard jacket and dark trousers as she strolls hand-in-hand with boyfriend Lucas Zwirner in NYC

They first sparked dating rumours in January this year after being spotted for the first time packing on the PDA in New York City.

And Sienna Miller cut a stylish figure as she went for a stroll with her boyfriend Lucas Zwirner in New York City on Friday.

The actress, 37, in a Mongolian cashmere Mandkhai jumper with a turtle neck which she paired with dark trousers.

Out and about: Sienna Miller, 37, cut a stylish figure as she went for a stroll with her boyfriend Lucas Zwirner, 28, in New York City on Friday

Out and about: Sienna Miller, 37, cut a stylish figure as she went for a stroll with her boyfriend Lucas Zwirner, 28, in New York City on Friday

The film star also sported a mustard woolly bomber jacket and a pair of black trainers while she let her blonde locks fall loose down her shoulders.

Sporting a black designer handbag and a pair of diamond earrings, Sienna looked in high spirits as she held hands with her boyfriend. 

Lucas, 28, sported a cream jacket and white trousers for his outing with Sienna and also wore black shoes brown shoes and a pair of spectacles.

Sienna's outing comes shortly after her appearance on BBC's The Graham Norton Show.

Casual: The actress in a Mongolian cashmere Mandkhai  jumper with a turtle neck which she paired with dark trousers and a mustard jacket

Casual: The actress in a Mongolian cashmere Mandkhai  jumper with a turtle neck which she paired with dark trousers and a mustard jacket

During her appearance on the chat show, Sienna spoke about her role in the mini-series, The Loudest Voice.

The actress transformed into Beth Ailes, the wife of former Fox News CEO Roger Ailes, in the show - which saw her undergo four hours of prosthetics every day.

Sienna detailed how she would get Lucas to passionately kiss her in the street - while wearing facial prosthetics, leaving tourists 'horrified.'

Asked about playing a character 20 years older than herself, the Layer Cake star said: 'I used to take ‘her’ for walks and into bars. I walked down the street with my quite young-looking boyfriend and asked him to kiss me passionately in front of a crowd of tourists.

'They were horrified at the sight of this young boy kissing his nana!'

Change: During her appearance on The Graham Norton Show, Sienna spoke about her role in the mini-series, The Loudest Voice, where she played Roger Ailes' wife Beth
Change: During her appearance on The Graham Norton Show, Sienna spoke about her role in the mini-series, The Loudest Voice, where she played Roger Ailes' wife Beth

Change: During her appearance on The Graham Norton Show, Sienna spoke about her role in the mini-series, The Loudest Voice, where she played Roger Ailes' wife Beth 

Sienna previously told how she enjoyed the experience of wearing prosthetics because it made both she and co-star Russell Crowe, 55, 'unrecognisable'.

Appearing on This Morning, she said: 'Russell Crowe had a lot [of prosthetics] on. It was a four-hour job, everyday for a long time.

'For the first three days I was laughing a lot, we were completely unrecognisable. But I found it liberating as it's a mask.'

The drama charted the executive's career and the allegations of sexual harassment against him.

Ailes was named chairman of Fox News in 2005 and, following his resignation, became an advisor to Donald Trump's presidential campaign where he assisted with debate preparation.

He died in 2017 aged 77 after falling and hitting his head at his home in Palm Beach, Florida.

Couple: The drama charted the executive's career and the allegations of sexual harassment against him (above with co-star Russell Crowe as Roger Ailes)

Couple: The drama charted the executive's career and the allegations of sexual harassment against him (above with co-star Russell Crowe as Roger Ailes)

Sienna Miller cuts a casual figure as she strolls hand-in-hand with boyfriend Lucas Zwirner in NYC 

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