Paltrow wore a Valentino dress

The screening of the film, about the poet Sylvia Plath, closed the London Film Festival.

The festival opened two weeks ago with thriller In the Cut. Films from more than 45 countries have been shown.

Paltrow's boyfriend, Coldplay's Chris Martin, was present at the premi�re. He told reporters the film was "the best I've ever seen".

The biopic Sylvia, directed by Christine Jeffs, has already caused controversy ahead of its release in January.

The daughter of Plath and Ted Hughes, Frieda Hughes, has accused the makers of cashing in on her mother's suicide and the tempestuous relationship between her parents.

She is really astounding. She became Sylvia Plath Sylvia writer, John Brownlow Premiere: in pictures

Paltrow said she felt a great responsibility in playing a non-fictional character.

"Especially someone like Sylvia Plath, who was so brilliant and so complicated.

"What I really love about the film is that the director approached the film from an emotional truth rather than an empirical truth."

Beginning in 1956, the film depicts Plath's history of depression and suicide attempts, and follows her tempestuous relationship with Hughes until her suicide in 1963.

The screening attracted a number of celebrity guests, but not the usual mix of soap stars and TV presenters that are often in attendance at premi�res.

MTV Awards? What awards?

Guests included Culture Secretary Tessa Jowell, BBC director general Greg Dyke and BBC executive and presenter Alan Yentob.

Chris Martin appeared despite the fact his band was competing for prizes at the MTV Awards in Edinburgh, being held at the same time.

Coldplay won best group at the awards.

The singer did not arrive with his partner Paltrow, arriving earlier with bandmates and ignoring most questions thrown at him.

Paltrow said she did a lot research for the part, reading all her poems, letters, her journals and her novel the Bell Jar, which she said she had first read aged 21.

"I spoke to two of her friends as well, so that was very helpful."

Affinity

However, most of the assembled media were more interested in her life in London and a reported move to Spain.

"I'm afraid you will have to get used to me," she said after being asked about her affinity with London.

Asked about a move to Spain, she said: "Wow, that would be nice. I wish it were true.

The film faces an uphill task in persuading people who know little about Plath to see the movie.

Few of the fans outside the cinema, in Leicester Square, knew who Sylvia Plath was.

"Was she a romantic poet?" asked Katie, from London, who knew more than most about the American poet.

Writer John Brownlow, praised Paltrow's performance.

He said: "She is really astounding. She became Sylvia Plath."

He said the film was not about poetry.

"It's a movie for general audiences. It is one of the great love stories of the last century."