Fitzroy police, he was released from his unit to work as a social worker in the Fitzroy Aboriginal community. He cared for those trapped in alcohol abuse, gambling, and other social problems, and those who were in trouble with the police. Indigenous people gathered to him and eventually the group was so large that he became the pastor of the first Aboriginal Church of Christ in Australia. In recognition of the ministry he was already expressing, he was ordained as a minister. In a letter to the editor, in 1953, it was noted that Opposition Leader, H. V. Evatt, had asked the Prime Minister Robert Menzies, on 26 February, in Federal Parliament, 'for an invitation to be extended to Capt. Reg Saunders or some other outstanding representative of the aborigines' to be included in the official Australian contingent to the coronation of Elizabeth II. The author suggested Nicholls, as an ordained minister, and for his community work in the areas of Fitzroy and Mooroopna. In 1957 Nicholls became a field officer for the Aborigines Advancement League. He edited their magazine, Smoke Signals, and helped draw Aboriginal issues to the attention of Government officials and the general public. He pleaded for dignity for Aboriginal people as human beings. Support for the AAL grew rapidly. Nicholls helped set up hostels for Aboriginal children, holiday homes for Aboriginal people at Queenscliff and was a founding member and Victorian Secretary of the Federal Council for the Advancement of Aborigines and Torres Strait Islanders (FCAATSI). In response to protests in the 1950s and 60s for an independent, Aboriginal-run farming cooperative at Lake Tyers Mission he campaigned on their behalf, but when the board moved to close Lake Tyers, Nichols resigned his position in protest. Nicholls was an active Freemason. Governor of South Australia Nicholls became Governor of South Australia on 1 December 1976, after being announced on May 25 on the nomination of Premier Don Dunstan. He was the first non-white person to serve as the governor of an Australian state, and is the only Aboriginal person to have held viceregal office. Because of his race, his nomination proved controversial and attracted more attention than most viceregal appointments. A poll by ABC's This Day Tonight found that 70 percent of respondents opposed Nicholls becoming governor. The Canberra Times expressed concern that members of his family might set up camp on the grounds of Government House.