It had promised to be a high-glamour affair with Britain's two hottest young starlets going head to head to be crowned queen of the red carpet.

Yet as Keira Knightley and Sienna Miller squared up for the premiere of their new film to open the Edinburgh Film Festival, it was left to a maturer star with a more established showbusiness heritage to provide the sparkle.

While Miss Knightley and Miss Miller dressed down in ill-advised more casual attire, Joely Richardson shimmered in a stunning floor-length golden gown showing off a curvaceous new figure.

Star of the show: Joely Richardson upstaged Sienna Miller and Keira Knightley at the Edge of Love premiere in a stunning floor-length golden gown

The younger women had clearly made an effort to create different looks for the world premiere of Edge of Love.

Miss Knightley, 23, wore a Chanel Jumpsuit and black Chanel cardigan while her co-star opted for a shapeless black tasselled dress by Jasmine de Milo topped with a rather bizarre vintage bowler hat.

They were both left in the shade by Miss Richardson who showed what two decades of red carpet experience can do.

But of course Joely, 43, has acting in the blood - indeed her heritage is steeped in it.

She is the daughter of Tony Richardson and Vanessa Redgrave, and granddaughter of actor Sir Michael Redgrave, she is the niece of Lynn Redgrave and her sister

Natasha Richardson is also an actress. Her former husband Tim Bevan is also a producer.

Co-stars: Sienna Miller and Keira Knightley kept somewhat covered up on the red carpet last night as they stepped out to promote their new film in Edinburgh

The two starlets' heritage does not stand up to such scrutiny.

Keira's father is an actor and mother is a playwright, even though legend has it she demanded an agent at the tender age of three.

Sienna's equally bohemian mother Jo, a sixties siren, ran London's Lee Strasburg acting school and dated David Bowie. Though she has dated a few actors in her time - notably Matthew Rhys, Daniel Craig and Law - all of whom she starred alongside.

Unlike the hoards of screaming fans expected at venues such as London's Leicester Square the premiere was a low-key affair with no more than 200 fans in attendance.
As well as being adversaries in the glamour stakes, the pair play love rivals in the biopic of Welsh poet Dylan Thomas, played by Matthew Rhys.

Last night Miss Miller dismissed any rivalry with her costar and said: 'She is one of my favourite girls'.

Mr Rhys posed with them amid reports that it was the closeness between him and Miss Miller which  recently broke off her romance with Notting Hill actor Rhys Ifans.

Miss Miller is cast as Caitlin MacNamara, Thomas's wife, while Miss Knightley took on the role of Vera Philips - the childhood sweetheart who returned to fight for her former lover's affections.

The film also stars Irish actor Cillian Murphy who plays Knightley's devoted husband William Killick.

The screenplay was written by Miss Knightley's mother Sharman Macdonald and it was a her daughter who persuaded director John Maybury to take it on.

Miss Macdonald had originally written the part of Caitlin for her daughter while on location in the Bahamas while she filmed Pirates of the Caribbean.

It was certainly Miss Knightley's star power which dominated the press conference and premiere yesterday putting her co-star, who is three years her older, in the shade.

The 23 year-old is a firm Hollywood favourite with an Oscar nomination for her performance in Pride and Prejudice and a fanbase from the Pirates of the Caribbean trilogy which first hit screens in 2003.

The current face of Chanel her £3 million contract will end this summer and she has an estimated fortune of £18 million.

Meanwhile Miss Miller has long been dubbed 'one to watch' without yet having a box office hit.

She first found fame as Jude Law's fiancee who she met on the set of Alfie, a film in which she had a small part.

She continued to generate headlines as the poster child of boho chic and then as the betrayed fiancee after it was revealed that Law had an affair with his children's nanny in 2006.

The Edge of Love is her highest profile role to date though she announced yesterday she will star alongside Russell Crowe as Maid Marian in a remake of Robin Hood.