@bobsal u1553115,
I imagine he was considered a 'new deal' socialist (the Snowy Mountains Hydro Project not being dissimilar to Roosevelt's Hoover Dam).
What's particularly odd is that our other major party is the Labor Party, which is funded partly but significantly by the union movement. I was born in the Menzies era but I don't remember him or Holt as PM - I think I remember Gorton, but definitely McMahon on.