The pair hummed songs after sharing a kiss in a love scene of the 1950s drama The Girl, which is being filmed at locations around Cape Town.

Biondi's modelling portfolio includes a cover shoot for Men's Health magazine.

Miller co-starred with her ex-fiancé Jude Law in Alfieand later became tabloid fodder when he cheated on her with his children's nanny.

Said raven-haired Biondi: "The kissing scene with Sienna was amazing and, from a professional point of view, it was the best kiss ever.

"Sienna is a lovely, humble person, a regular girl and a wonderful actress. Working with her was real easy. We both love [UK band] The Smiths and ended up singing the songs together."

An HBO and BBC co-production, The Girl chronicles filmmaker Alfred Hitchcock's obsessive relationship with actress Tippi Hedren, played by Miller.

Biondi portrays Sean Connery, with whom Hedren co-starred in the 1964 Hitchcock film Marnie.

On Monday the Artscape Theatre in Cape Town was transformed into a 1950s cinema for the movie. Miller had a simple lunch of fish and chips (R35) and red Grapetiser at the theatre's cafe.

Staff said she left a R20 tip.

Miller's new beau, actor Tom Sturridge, who is rumoured to be the father of her unborn child, visited her in Cape Town.

The couple was spotted at Little Beta beach in Bakoven this week and dined on prawn spaghetti and tomato soup at Societi Bistro in Orange Street two weeks ago.

Miller's mother, Josephine, a New York film school manager, was also seen by her side on the film sets.

Local production company Moonlighting did not respond to questions.