This article is a contribution to the cultural history of English Enlightenment. It examines the formation of a discrete ‘family’ of philosophes in the West Midlands who maintained close links with their counterparts on the continent. Birmingham's role as a magnet for ‘industrial tourists’ in the second half of the eighteenth century helped to propagate the influence of this local intelligentsia who were mostly members of the Lunar Society. None the less, it is argued that the activities of the Society correspond more closely to an Enlightenment than to a proto-industrial pattern of inquiry. The events of 1789 in France disrupted this philosophic ‘family’. Their impact is explored through the medium of a real family; that of James Watt, the engineer, who came to Birmingham to manufacture the steam engine in partnership with Matthew Boulton. The vicissitudes of the Watt family, and of other prominent members of the Lunar Society, are unravelled to illustrate the dilemmas faced by men raised in the values of the Enlightenment when confronted with the reality – and the proximity – of a far-reaching political revolution.