A little late, but I would like to add my tidbit of news on accents.
In David Lean’s (Arguably Britain’s greatest film director, Lawrence of Arabia, Doctor Zhivago, The Bridge on the River Kwai) film Ryan’s Daughter,(perhaps Lean’s worst film) Christopher Jones was an American movie star and one of the principal stars in the film. He was portraying an English officer. He had his entire voice dubbed over in the film. Jones in the 1970s was at the height of his career and had the potential of being one of America’s biggest movie stars. After Ryan’s daughter his career went into complete oblivion; he became virtually a non-entity in Hollywood, very sad.
One of the many rumors was that he couldn’t deal with his voice being dubbed in the film. Lean had Jones’ voice dubbed after completion of the film and this had a disturbing affect on Jones and a negative affect on his reputation.
There were obviously other serious circumstances that contributed to his demise.