He toured Australia with a gumleaf orchestra during the Great Depression of the 1930s, played rugby league and became a respected elder who campaigned for protection of sacred sites on the South Coast.
Guboo was son of William "Bill" Iberia Thomas, a tribal elder, and Mary Gwendoline "Linno" Ahoy, a woman of Chinese descent.
Thomas also knew that she had French blood as her mother's surname had been de Mestre; his French great-great-grandfather Prosper de Mestre (1789–1844) was a prominent businessman in Sydney from 1818 to 1844, while his Chinese grandfather James Ahoy was a market gardener in the Braidwood area at the time of the gold rush, who moved back to China leaving his family behind.
When he was nine, his father, uncle and other Yuin elders took him on their Dreamtime walkabout from Mallacoota on the Victorian border to the Hawkesbury River and showed him all the sacred sites for which he would later be responsible.
The Gumleaf Band played at football dances, and on the back of trucks at district shows, gymkhanas, and sports picnics on the beach.
He used these trips to visit Aboriginal missions from Victoria, up the New South Wales coast into Queensland, and inland over the Great Dividing Range.
He would visit the old people to learn more about their customs and beliefs, tour their sacred sites and talk to them about protecting the land and the Great Spirit that sustained it.
Most of his working life, however, was spent as a commercial fisherman on the South Coast applying that special knowledge given to him by his elders, except that "the middleman made all the money".
In the early 1970s Thomas and his wife Ann and other tribal Elders joined Pastor Frank Roberts' New South Wales Aboriginal Lands and Rights Council.
His activism began by hitchhiking to Canberra to urge the Government to make the Wallaga Lake Aboriginal Station into a reserve and to seek protection of the sacred sites.
The New South Wales National Parks and Wildlife Service, with the help of Thomas, commenced an Anthropological and Archaeological investigation of Mumbulla Mountain.
[citation needed] Around this time, he began espousing a spiritual message, believing that the noisy protests and marches only aggravated racism.
He wanted the Dreaming to enrich the lives of all Australians, and devoted the rest of his life to being a catalyst for a worldwide return to selfless ancient values.
Unfortunately he also sometimes upset the actual traditional owners of the land where his ceremonies were held, by not always respecting their sacred sites, and by violating local Aboriginal laws.
[20] Ever the gentle activist, in February 2002 he took part in a protest at Sandon Point near Wollongong demonstrating against a development threatening Aboriginal sites and the area's natural beauty.
[citation needed] Active in what he saw as his life's work till the very end, in his last days he participated in a study about Indigenous kinship with the Natural World in New South Wales.
[citation needed] Thomas's work in developing mutual respect and understanding, and in the renewal of the Spirit and the Dreaming, was prolific and ongoing.