The script held in the Crawford Collection in the AFI Research Collection contains the following character notes (excluding regular characters):
'BILL BENSON 70 Years old [sic]. Known locally as "Strike Me Die" Benson, also known for his penchant for malapropisms. An old royalist and member of the ninth division in the first world war [sic]. He tries to appear stern and ornery most of the time but this is just a cover for a lonely old man. He loves his dog "Sergeant" but tries not to allow this to show, he treats him like a soldier of the lower rank.
'HARRY RILEY 45 years old. From Melbourne. A mean, weasly, sour-faced looking individual. Flashily dressed, he thinks all country people are hicks. Only one thing in life is important and that's Harry Riley.
'VERA RILEY 40 years old. From Melbourne. A plain looking woman, would probably still be single except that she decided that Harry was better than having no husband at all. She is completely dominated by him.
[...]
'SERGEANT Benson's dog. A large animal, slightly scruffy looking. Probably an Alsation cross breed.'