Dissuaded from following a military career, he joined his father in a short-lived attempt to set up a mission at Gascoyne River in Western Australia.
After a time working as a stockman and drover, Ernest accepted a curacy at Tumbarumba in New South Wales for financial reasons.
In 1892 John Brown Gribble, who had opened a mission at Yarrabah in Queensland, fell ill, and called on Ernest to take it over in his stead.
[5] Gribble showed little comprehension of Aboriginal culture, failing to learn even elementary words of the local language at Yarrabah, which he eventually left in 1909, after suffering a breakdown[4] from overwork according to Harris,[5] from guilt over having a child with an Aboriginal woman in 1908, a year after he separated from his wife Emilie Julie Wriede.
[4] Under his administration, the sexes were segregated; children were isolated from their parents and relatives by being confined to dormitories, and generally, he seems to have instituted the kind of military barracks system of regimentation, with uniforms, parades and policing, typical of the career he aspired to as a youth.
His activism led to him being shunned by the non-Aboriginal community, and he was dismissed soon afterwards, in 1928, contributing factors being his mismanagement of finances, and the discovery that he had hidden from police investigators facts that would have implicated an Aboriginal resident at the mission in a tribal murder.