An unlikely friendship has blossomed between co-stars Keira Knightley and Sienna Miller.

The girls, who are currently filming The Edge Of Love – a film about Dylan Thomas – together, hit the town last night with Keira’s fella Rupert Friend and their other co-star Matthew Rhys in tow.

Sienna’s boyfriend Jamie Burke was suspiciously absent, despite the fact he is in London at the moment, but it clearly wasn’t stopping Sienna from having a good time.

The gang went for dinner in Archipelago before having a very schoolkid moment of linking arms while running down the street.

In the film the two feisty, free-spirited women are connected by the charismatic poet, who loves them both.

It is understood that the script features a sexy threesome with the two women and the poet, and has been described as “very steamy” by those who have seen a sneak preview.

As we revealed earlier this week, 25-year-old Sienna stepped into the role of Caitlin MacNamara – Thomas’s wife – in the movie when Lindsay Lohan pulled out after she was asked to take a drugs test.

We’re told Sienna and 22- year-old Keira have become inseparable on the set in New Quay, Wales, so much so they are currently househunting for neighbouring cottages overlooking the sea there.

We’re told: “Sienna and Keira feel it would be great to have homes there and go on joint holidays once filming stops, so they can keep up their friendship.

The source added: “They’re actively hunting for the perfect cottages in the area.”

Source