The kids voices are from the Laurence Olivier WH movie. Im sure of it.
The children from the movie were Sarita Wooten, Rex Downing and Douglas Scott. All three are listed in the credits here.
What accent does De Mille have?
Just checked--born in Massachusetts, grew up in New York City and mother was from London.
I'm shocked that this particular adaptation didn't require 2 weeks and 6 acts, the story is quite long and involved.