Observation....Speculation
When Horace married Maud Feb 1917 he had not been to Australia at all.
He had probable relatives in Kalgoorlie involved in mining and new of them.
He was still in the Army Foot Police at the marriage (quit May 1917)
He invented an occupation which was a bit true (police) and a bit wishful/false in order to obscure his identity. (Mounted police Australia)
In August 1917 he embarked for South Africa from Liverpool. Maud was pregnant.
Horace Verdum William GUNDRY. Births Sep 1/4 1917
Mother HOLLLANDS
At Orsett
4a 886
He returned to father another child and in 1921 they all set of for Western Australia to make use of his mining experience.
How his "first wife" Alice knew of his exploits and his mining career is a mystery. But with youngish children to care for, she was not admitting desertion and knew of his whereabouts in order to claim his pension.
My thoughts on the matter for your entertainment

Sue