Jane Austen’s books make excellent period dramas but actresses who play her most famous heroines are not, according to the author’s biographer.

Paula Byrne launched a scathing attack on Kiera Knightley, Gwyneth Paltrow and Emma Thompson for their portrayals in the film adaptations.

Speaking at the Hay Festival of Arts and Literature, Dr Byrne said that Miss Paltrow and Miss Knightley had a ‘nasal whine’ and Miss Thompson was ‘too old’.

Dr Byrne, a well respected academic, said that the director was so in love with Miss Paltrow, who played Emma Woodhouse in the film adaptation, that they both got the character totally wrong.

Dr Byrne said Gwyneth Paltrow, who played Emma Woodhouse in the film adaptation, got the character totally wrong, while she criticised Keira Knightley for having a 'whiney' voice

‘Gwyneth Paltrow in Emma I didn’t like,’ she said. ‘There was no sense in which she was ironised, the point of her is she’s constantly getting it wrong.

‘Whereas I thought the director was so in love with Gwyneth Paltrow - she looks beautiful in every shot - you didn’t get a sense of the director poking fun of her which is so much a part of her character.’

She added: ‘That voice, that nasal whine - it just drives me mad. It’s like Keira Knightley - she’s got that nasal thing going on too. I want to just strangle her.’

Miss Knightley played Elizabeth Bennett in the 2005 film Pride and Prejudice in a role that would launch her career.

But Dr Byrne said: ‘I didn’t like Keira Knightley at all.

‘I thought she was completely wrong for Elizabeth Bennett. She has a great back, a beautiful back, and all we can see is her back. I found her quite wooden and she doesn’t articulate very well.

Speaking at the Hay Festival of Arts and Literature, Dr Byrne said that Miss Paltrow (pictured left, in Emma) and Miss Knightley had a ‘nasal whine’ and Miss Thompson was ‘too old’

‘She is way too beautiful for Elizabeth because the one thing we know about Elizabeth is that her sister is very beautiful but Elizabeth just has fine eyes and that’s all we know about Elizabeth, that she has fine eyes.’

Dr Byrne said she was a fan of the film Clueless, which is a modern day re-telling of Emma starring Alicia Silverstone and Brittany Murphy.

‘I think Jane Austen would have loved Clueless,’ said Dr Byrne.

‘It’s laugh out loud funny, but I think she would probably be less pleased with Gwyneth Paltrow’s Emma which was too romantic.’

On Miss Thompson in Sense and Sensibility she said: ‘Emma Thompson was way too old, she’s playing a 17 or 18 year old - I think she was 43, so I’m not quite sure that worked. We forget how young the heroines are.’

Dr Byrne added that the houses in the films were ‘way too big’ because Austen was not writing about the aristocracy.

Emma Thompson and Hugh Grant in Sense and Sensibility (left). Pictured right is Dr Byrne, a well respected academic

Dr Byrne lives in Oxford with her husband, the Shakespeare scholar Sir Jonathan Bate, and their three children, Tom, Ellie and Harry.

In January 2013, to coincide with the bicentenary of the first publication of Pride and Prejudice, she published a biography called The Real Jane Austen: A Life in Small Things.

Last month Dr Byrne was unwittingly drawn into a plagiarism row.

The Private Eye magazine drew a number of comparisons between Lucy Worsley’s biography Jane Austen at Home and Dr Byrne’s 2013 book.

They claimed that there were ten similarities between the two books.

Miss Worsley, the chief curator of Historic Royal Palaces, issued a strong denial.

Dr Byrne said she would reserve judgment until she saw Miss Worsley’s book.