For actors who want to know how the authentic, middle class, standard English accent of the 1930s and early 1940s sounds, go to the “ Writing Britain – Wastelands and Wonderlands” exhibition at the British Library.  There is a fantastic recording of an interview by Pamela Howe of Stella Gibbons on Woman’s Hour, recorded in 1974.
Stella Gibbon’s voice is clear and strong and sounds much younger than her 72 years.  She has the extended back of the neck sound of the 1930s and early 40s.  The slower movement of the lips and the precise placement of the blade of the tongue sound attractive because they’re supported by Stella Gibbons’ bell like voice and obvious happiness in talking about her novel, Cold Comfort Farm, first published in 1933.  Both women are unaffected by the “Sloane” loose lipped dialect that was big in London in the mid 70s.
The exhibition closes on September 25^th but you can still hear the recording afterwards, if you’re a member of the British Library.
http://www.bl.uk/whatson/exhibitions/writingbritain/about/index.html