Bill O'Brien was born out in the country at Bedellick, past the village of Hall, towards Yass, along Spring Range Road, where his father selected land, as a pioneer of the area. His grandfather, John, arrived in Australia from Limerick, Ireland, in 1849 (approx.). Some of the families that settled in that area were, Brown, Butler, Flanagan, Gozzard, Harcourt, Hatch, Kilby, Ryan, Shumack and Southwell. Bill's father, Matthew, was born at Ginninderra in 1855.
Bill attended school at Bedellick, on the property of “Fairview”, previously named “Cow Hollow”. The school was destroyed by fire in 1904, the remains of the schoolhouse can be found today (2019) along Namina Road, although recently (2019), a large concrete block was placed there which obstructs the view of the remains.