Although the Whitehall plan may have been sucked deep into a bureaucratic vortex, it is important to recall the particular values of the particular time which had earlier made it possible: the brief but remarkable moment in British history between the enthusiasm for an impending jet-age, associated with Harold Wilson’s famous speech of 1963, and the evaporation of that optimism during the government’s reaction to the sterling crisis of 1966. We have outlined here the distinctive values that made the systems-planned megastructure, and its associated public spaces, not just plausible but desirable at the moment of White Heat. Computed for a new computer era, it emerged from – and, to some extent, helped to consolidate – a conjunction of political priorities and architectural ideas that would have seemed unlikely either before or after. Surprisingly, the impetus for rebuilding the marble halls of government came from within, from a prevailing sense of an imminent technological future which Britain urgently needed to prepare for. Modernising instincts were prevalent and they contradicted the stereotypes of the time. Neophile tendencies were shared widely: among senior civil servants, countering the stereotype of Sir Humphreys habitually averse to change; among leading Conservatives, who belied the impression of ‘amiable coelacanths’ stuck in Edwardian ways; and also among some senior Labour gures, whose radical impulses ran less deep than is often assumed.