April 28: Judi Dench has criticised actors who fail to speak properly while performing, as well as young actors who have no interest in the legacy of acting greats from earlier generations.

Speaking at the unveiling of an English Heritage blue plaque dedicated to her friend John Gielgud, Dench said she wished a new generation would want to learn more about him and his peers.

"What is so shocking now is that young actors don't want to find out about the legacy that we've been left," she said.

"They don't want to know about [David] Garrick and [Sir Henry] Irving and Peggy Ashcroft and Edith Evans, and that seems to me to be a terrible shame.

"Because although the fashion now may not be to speak the way that John and Peggy and Ralph [Richardson] and Laurence [Olivier] spoke, nevertheless if you listen to John you will always get what Shakespeare means.

"They're just not curious. It's just non-curiosity. I think it's terribly important to know the huge history of theatre that we have, why you're in it, what people did before, the lives of actors."

Dench, who worked with Gielgud for many years, said she had been "devoted" to him after he boosted her confidence as a young actress working on The Cherry Orchard, consoling her after an encounter with a fierce director to tell her he would have been "delighted" by her performance.

Speaking underneath the new plaque, at 16 Cowley Street in Westminster, Dench went on to hit out at productions where the audience was unable to understand the actors' words - singling out the BBC's 2014 adaptation of Jamaica Inn.

"I know [the drama was based in] Cornwall, but it was ridiculous," she said.

"Often I want to shout out, 'Will you say that again because I can't hear!' It is an apathy, laziness. If you're not going to be heard, then stay at home and do it in your living room.

"It doesn't require shouting, it requires learning about it and learning where your voice comes from, where your diaphragm is and how to use it."