Shortly after stepping down as Viceroy of India, Lord Curzon remarked that “It has been the policy of Protectorates that the Indian Empire has for more than a century pursued, and is still pursuing, its as yet unexhausted advance” (p. vii). Taking Curzon's words as his starting point, James Onley focuses on the Arabian frontier of the British raj. Indeed, one of Onley's most penetrating conclusions is that “the Indian Empire was much larger than current Indian historiography says it was, and that the informal part of this empire included Arabia” (p. 216). Taking his analysis still further, Onley remarks that “it becomes apparent that British India itself had an informal sub-empire in South Asia, Arabia, and East Africa comprised of semi-independent states under the suzerainty of the British Crown' (pp. 216–217). It is the semi-independent states of the Gulf on which Onley's book concentrates. One of the most significant aspects of his excellent book is British reliance on ‘native agents’ for the maintenance of imperial interests and influence in the region throughout the nineteenth century.

“The history of British India's residency system, especially the Gulf Residency”, argues Onley, “. . . illustrates how important Britain's native agents were, not only for the intelligence and mediation that only indigenous representatives could provide, but also for making informal empire affordable for the British” (p. 12). At first, the British recruited native agents from among the Bania, or Hindu merchant communities from both India and the Gulf itself. In 1834, however, the al Khalifah ruling family of Bahrain objected which started a process leading the British eventually to employ Muslim merchants, both Arab and Persian, as native agents. The British recruited such non-European agents, Onley notes, “because of the lack of British officers, because of the agents' local knowledge, and because of the agents' willingness to work for nominal salaries” (p. 103). Merchants' families allied themselves to the East India Company, and subsequently to the British-dominated Government of India, in order to gain protection for themselves, their businesses and families. Collaboration with the British also offered the prospect of an improved social status, increased power over rivals, and improved business opportunities. Onley explains that the intrinsic demerits in the native agency system, namely the potential for conflict between trade and politics and the production of intelligence reports which were not always entirely accurate, were tolerated provided that agents remained influential with local potentates and upheld British interests. So successful was the system that British Residents entrusted native agents with more and more responsibility as the century progressed. “The result, paradoxically”, observes Onley, “was an expanding political role for non-Europeans in the Gulf Residency at a time when the role of non-Europeans in the Indian residencies was diminishing”. (p. 82)

The decline of the native agency system from the end of the nineteenth century and its replacement with a political agency system was due, insists Onley, to increasing imperial rivalry in the region and for the concomitant need for a stronger British presence. “Had international rivalry in the Gulf not increased,” he argues, “the native agency system in Bahrain could have continued to function adequately for its established purpose” (p. 214). Onley draws a wider conclusion from this observation, namely that Ronald Robinson's claim that the breakdown of systems of indigenous collaboration led to a transition from indirect to more direct forms of imperial control requires modification. Indeed, he argues that the example provided by the Gulf demonstrates that “indigenous systems of mediation and collaboration do not have to break down to lead to more direct forms of imperial control”. (p. 223) Even after the increase in direct British supervision by political agencies, Onley notes that “British political agents in the Gulf continued to rely heavily on the intelligence and mediation provided by their native political assistants, and on various other services provided by large native staffs, until the end of the Gulf Residency in 1971”. (p. 222)

The British empire in the Gulf in the twentieth century has attracted a considerable degree of historical interest, reflected in the growing number of publications on the subject. The nineteenth century, by contrast, has been relatively neglected which makes the publication of James Onley's book especially welcome. His work, founded on extensive research in both Britain and the Gulf itself, produces incisive conclusions which add greatly to our understanding of British methods of control in the informal empire.