In 1935, Nell married Dr Wallis Verco Ludbrook, a plant pathologist, whom she had met at the University of Adelaide where he was studying for his B.Sc., and they moved to Canberra. Irene Crespin, palaeontologist with the Commonwealth government employed Nell as an Assistant Geologist from 1942 to 1949, working on the statistics of minerals for the war effort at the Commonwealth’s Mineral Resources Survey in Canberra (forerunner of the Bureau of Mineral Resources).
In 1950, while Wallis was away for work, Nell travelled to England to study molluscs at the Imperial College of Science at the British Natural History Museum. Wallis died in 1951, and Nelly was encouraged by his family to remain in England and undertake her PhD, which she received in 1952 from the University of London for her research into Pliocene molluscs of the Adelaide plains. In 1950 she had become a Fellow of the Geological Society, London.
She then returned to Australia and worked within the South Australian Department of Mines from 1952 until 1967, at which point she had attained the position of Senior Palaeontologist, specialising in the palaeontology and biostratigraphy of the Eromanga and other South Australian basins. She then continued as a consultant in palaeontology and editor after her retirement. Nelly Ludbrook has seventeen fossil species named after her and published over 70 scientific papers. She was appointed Member of the Order of the British Empire in 1981 for her service to science. A foundation member of the GSA, Nelly was its first female president in 1968 and first female president of the Royal Society of South Australia in 1961. She received the Sir Joseph Verco medal from the Royal Society in 1963. The Geological Survey of South Australia has named their fossil collection, the Ludbrook Library in her honour.
Alley, Neville F. (1996). "Obituary: Nelly Hooper Ludbrook". Transactions of the Royal Society of South Australia. 120 (2: 74-77). 2016, https://www.biodiversitylibrary.org/page/41319575#page/87/mode/1up, accessed 4 November 2019
Turner, S., 'Invincible but mostly Invisible: Australian Women's Contribution to Geology and Palaeontology', Geological Society Special Publication, vol. 281, 2007, pp. 165-202.