TWELVE-year-old, British-born, Kathryn Beaumont has the title role in Walt Disney’s most lavish and costly production, “Alice In Wonderland.” As the voice of Alice her accent is slight, at all times understandable and yet British enough to be authentic in the Lewis Carroll classic. A bright and alert young lady, Kathy has long heeded her voice and dramatic lessons so that when tested for the role of Alice by Disney she was well prepared and won it. She had previously appeared in a few pictures at MGM. In making “Alice In Wonderland,” Disney first had Kathy and the other “voices” actually do scenes for his animators to further familiarize them with how the characters would perform. This spectacular, all-cartoon animation, musical has taken several years of preparation, involving considerable research in order to have the beloved little heroine and all of her thrilling experiences with the creatures at the bottom of the rabbit hole faithfully presented.