Casting directors are lost for words because the next generation of British actors just cannot speak proper. The rise of “Estuary English” has left children with the intonation patterns of Lily Allen and Jonathan Ross, regardless of their background.

The decline in Received Pronunciation has not just transformed the presentation of BBC News. Film and drama producers are struggling to fill period roles that require unrepentantly middle-class vowels. BBC One is holding an open casting session tomorrow to try to find two girls to star in a film-length adaptation of the classic children’s novel Ballet Shoes. Victoria Wood and Marc Warren have signed up to star in the story, by Noel Streatfeild, set in 1930s London. But the challenge of finding two ballet-dancing leads who can act, twirl and – most importantly – speak in middle-class accents has defeated the producers.

“We’ve been to drama schools, ordinary schools and children’s agents, but we still haven’t found the right girls,” said Susie Parriss, the casting director.

“It doesn’t matter whether you go to public schools or comprehensives, children just speak common estuary now. That is the trend. But this story requires our leads to speak with a clear middle-class accent.” The great names of British theatre fear that young acting talent may never recover from a “mockney” upbringing. Scripts often have to be rewritten to accommodate actors trained in regional speech patterns at drama school. Dame Eileen Atkins, who appeared in the TV adaptation of David Copperfield in 2000, has told young actors that they will have to master Received Pronunciation if they want to take on important, classical roles. Otherwise, she said, they will play parlour maids forever.

Suzan Harrison, who produced an adaptation of Tom Brown’s School Days for ITV, found during casting that child actors had picked up an Antipodean lilt from watching Neighbours. However, accents that reveal privilege are often unacceptable among peer groups. John Wells, Professor of Phonetics at the University of London, said: “There is social pressure on some of those at the top of the socio-economic heap to reduce the linguistic differences between themselves and those in the middle of the heap.”

Ms Parriss said that producers no longer had time to play Professor Higgins to starlets. “It is hard to teach a middle-class accent,” she said. “We want the girls to be completely natural in front of the camera. There are already so many technical things that they have to learn.”

Ms Parriss is hoping that hundreds of well-spoken young actresses with wit, personality and the ability to dance en pointe, will present themselves in Central London tomorrow.

Ballet Shoes has been a bestseller since it was published in 1936. It tells the tale of the orphans Pauline, Petro-va – who has already been cast – and Posy Fossil, who are adopted by an eccentric explorer. It follows their struggle to fulfil their dreams.

The Ballet Shoes audition takes place at Bloomsbury Central Baptist Church, 235 Shaftesbury Avenue, London, at 10am tomorrow. Under16s must be accompanied by a parent or guardian. Hopefuls who would like a reading script should contact Ballet-shoescasting@gmail.com.

The shoes that are hard to fill

Posy
A talented ballet dancer, exceptional in every way and a little madam. She is a good mimic with a wicked sense of humour but passionate about dance, ambitious and focused. Has a playing age of 9 through to 12 so the BBC is interested in girls aged 11 to small 14-year-olds (5ft 2in or under). Posy will have to speak with a middle-class accent. Has to be able to dance en pointe and be prepared to dye her hair auburn if necessary.

Pauline
Blonde and very beautiful. She is a budding actress and also sings and dances. Pauline is intelligent, serious and quite driven, with a selfish streak. She also speaks with a general middle-class accent. This role ages from 13 to 15 and the producers are looking for a talented young actress who must have turned 16 before the end of the summer term and is 5ft 5in or under.

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