G'day Paul I'm glad you posted that one. I have spent many-an-hour researching Walmac.
I am not ready to write a record on Walmac Electrical Products yet. ... I need more time to do that.
I feel comfortable in saying this: - Walmac was formed post WWII and gained notoriety in the manufacture of gas and electrical stoves and florescent lighting units.
By the early 1960s, it expanded into other consumer goods, including the manufacture of lawnmowers.
I am almost certain that Walmac made many HG Palmer branded lawnmowers. I know Walmac had the capacity and experience to do this.
The mower factory was located at 23 Lusty Street, Arncliffe, NSW. That was not their first address, nor their last.