Doubts about the origin of Bentham's formula, ‘the greatest happiness of the greatest number’, were resolved by Robert Shackleton thirty years ago. Uncertainty has persisted on at least two points. (1) Why did the phrase largely disappear from Bentham's writing for three or four decades after its appearance in 1776? (2) Is it correct to argue (with David Lyons in 1973) that Bentham's principle is to be differentially interpreted as having sometimes a ‘parochial’ and sometimes a ‘universalist’ bearing? These issues are reopened here with particular reference to textual evidence overlooked in earlier discussions and contextual evidence on the development of Bentham's radicalism in the last two decades of his life. In conclusion some broader issues are raised concerning the character of Bentham's understanding of ‘happiness’ itself.