His 1980 D.Phil thesis at the University of Oxford was titled "The rebellion in Awadh, 1857-1858: a study in popular resistance". He has revisited his view of the revolt from the native perspective in books including Awadh in Revolt 1857-58: A Study of Popular Resistance (Delhi, 1984, repr. 2002), Spectre of Violence: The 1857 Kanpur Massacres (Delhi, 1988), and Mangal Pandey: Brave Martyr or Accidental Hero? (Penguin India).
He has taught history at the University of Calcutta and held visiting appointments at Princeton University, the University of Manchester, the University of California, Santa Cruz and the Young India Fellowship, New Delhi. At the Centre for Studies in Social Sciences, Calcutta (CSSSC), which he had joined as a Junior Research Fellow in 1975, he was involved in issues concerning the ascendancy of the North in the production of knowledge. He has edited The Penguin Gandhi Reader (Delhi, 1993) and is the author of the Art of Bengal: A Vision Defined, 1955-75 (Kolkata, 2003), and co-edited Trade and Politics and the Indian Ocean World: Essays in Honour of Ashin Das Gupta (Delhi, 1998).
He has also worked on the history of the leftist movement in India. After the 2007 Nandigram episode, he was among those leftist intellectuals in Kolkata who protested the violent policies of the left.