The recipe for this "inexpensive and quickly-made white vegetable soup" is from Household Notes in the Sydney Morning Herald on 5 May 1928. I'm not sure about boiling the vegetables for 40 minutes and thickening the finished product with flour though. Instead I've updated the cooking time to 20-30 minutes and enriched it with a little cream.
4 cups water
Peel the vegetables and cut up in small pieces. Melt the butter in a saucepan; add vegetables, and cook, stirring, until all the butter is absorbed. Add salt, pepper, sugar, mace, and water; simmer till vegetables are soft enough to rub through a sieve (20-30 minutes cooking should be sufficient).
Sieve (or puree) the soup; add milk and return to the saucepan. Add cream; let it come to the boil. Serve in a warmed tureen and bowls. Serves 6.