It has now been more than a decade since the Foreign and Commonwealth Office was forced to reveal the existence of a secret archive at the Hanslope Park intelligence facility in Buckinghamshire. As decolonization accelerated in the 1950s and 1960s, hundreds of thousands of files were wrenched free from archival procedures that would have made them accessible to officials of the new states that emerged from the empire or to members of the public in Britain. A 1961 Colonial Office directive made clear that this special handling was specifically intended for materials that “might embarrass Her Majesty’s Government.” Roughly 20,000 such files ended up at Hanslope Park while many more were destroyed on the spot.

Since 2011, this collection has gradually been transferred to the National Archives of the United Kingdom and opened to the public. The consensus among historians is that revelations from the files so far have been incremental rather than revolutionary. But unsettling questions about the politics of historical writing continue to linger. If it had not been for a lawsuit brought by survivors of the brutal British counterinsurgency in 1950s Kenya, the Hanslope Park archive would likely never have come to light at all. How can the history of British imperialism—and above all the “embarrassment” of its violence against British subjects—be salvaged from archives painstakingly crafted and sanitized by imperial rulers? Of course, all historians must construct their narratives from fragments of the past; they must likewise read against the grain of potentially misleading documents. But with seventy-five linear feet of colonial files apparently “lost” by the Foreign Office and another 600,000 “non-standard” files yet to be released, one has to ask whether a source base already overwhelmingly biased toward literate, Anglophone men can tell us much beyond the aspirational self-image of the ruling elite. The conspicuous black holes of official suppression threaten to make at least some aspects of imperial history one of those subjects, like the royal family or the Kennedy assassination, where constraints on scholarship have left a flourishing field to speculation and lore.

How to write a worthwhile history of empire after Hanslope Park was something I wrestled with when starting work on the book that would become Age of Emergency. I soon realized that the seductive drama of secrecy and revelation was not just a distraction but an active impediment to understanding Britain’s relationship with colonial violence. Too many observers had drawn the wrong conclusion from the archive scandal: that the brutality of imperial rule had long been “suppressed and buried,” as critic Paul Gilroy put it, and that the horrifying truth was only now emerging into the light of day. Besides overstating the importance of the Hanslope files themselves—and perhaps falling prey to what has been called the “fetishism” of secret files—these kinds of responses painted a highly questionable picture of the British past. My thoughts turned first to the 1950s: a period marked not only by intensely violent counterinsurgencies in colonies such as Kenya, Malaya, and Cyprus, but by record-high newspaper circulation, the advent of television, the conscription of ordinary men as soldiers, and fresh memories of the Second World War as a “good war.” Against this backdrop, was it really possible that British forces could torture suspects, carry out summary executions, and commit other atrocities in the colonies without people at home taking notice?