Florence Nightingale became a legend in her own lifetime and the image of the lady with the lamp still influences public thinking about the practice of nursing and its practitioners. Like many legends, her story has been adapted to suit changing circumstances and purposes. One could speculate why it is that particular aspects have come into greater prominence at particular times in history. This article explores a less-known aspect of her work, her expertise and use of statistics and epidemiology. And it illustrates how that expertise was called upon to address a major health problem in New Zealand in 1860.