Book of the Week: Replenishing the Earth, By James Belich

Politicians as well as historians have been debating the past and future of Britishness for some time, and few more assiduously than Gordon Brown. A few years back, he argued that "every central question about our national future... can only be fully answered if we are clear about what we value about being British". Future success, he urged, "depends upon us rediscovering from our history the shared values that bind us together and on us becoming more explicit about what we stand for as a nation".

Yet although Brown has gestured towards the global reach of Britishness, he has done so in an oddly, but perhaps typically, half-hearted way. He has called on "our maritime and trading traditions" which "have made us remarkably outward-looking and open". There's an intriguing silence there: invoking trade and seafaring but not migration or settlement, conquest or colonisation. Don't Mention the Empire – even if elsewhere Brown has suggested we should "stop apologising" for the imperial past. Overall, the recent flood of political rhetoric about re-inventing Britishness has, while making ritual noises about globalisation, openness and multiculture, remained astonishingly insular.

Britishness, though, was once truly global, and some historians have rediscovered an interest in that. The empire, they argue, was held together not just by ties of trade and defence but by a shared, worldwide sense of British identity. Terms like "the British diaspora", "Greater Britain", "Anglobalisation" and, above all, "the British World" have become increasingly popular in the past few years.

The concept was open to a vast variety of interpretations, at home and in the colonies settled by British emigrants. It was strongest where settlers of British origin were in the majority or, as in South Africa, formed a dominant minority. In some visions, it might embrace the United States too.

And it was not necessarily confined to people of British descent. Black West Indians, or South and West Africans, might find the idea of belonging to the empire appealing, not least if it helped them lay claim to principles upholding individual liberty, equal rights, and notions of progress.

James Belich's Replenishing the Earth is the biggest, boldest, most truly global and potentially most contentious of these renewed "British World" histories. Belich sets the story of the "Anglo-World" and its "settler revolution" between 1780 and 1930 in a wider frame of European-driven transformations. In his argument, European expansion took three successive forms: networks (especially of trade), empire (through conquest), and settlement.

The third was chronologically the last, but has had the most enduring effects. It was also the most distinctively European. Chinese, Mongols, Arabs and others preceded and long outmatched Europeans in long-distance trade and territorial conquest; but Europe's - and especially these islands' - mass export of population was unique.

There was, Belich argues, a uniquely Anglophone "settler revolution" across the long 19th century: "the Anglo divergence". It was explained and celebrated at the time in pseudo-racial terms, as a product of "Anglo-Saxonism" and its virtues. In reaction, today, there has been a tendency "to downplay, diminish, or even deny a genuine Anglophone divergence". Yet it was a phenomenon of such uniqueness, such global significance, that we cannot ignore it. We must seek new ways of explaining it – ways stripped of triumphalism and of semi-racial mystique.

Belich suggests four stages of British world colonisation: Incremental; Explosive; Recolonisation; and Decolonisation. The "incremental" stage was the relatively slow growth of settler populations from the 16th to the early 19th century. "Explosive" colonisation then ensued, driven by new pressures and opportunities. The agricultural and industrial revolutions were the most obvious, but there was also a crucial transformation in attitudes to settlerdom. "Before 1800, most Britons saw emigration as social excretion" – emigrants were abject or undesirable types. As the 19th century wore on, they came instead to be celebrated.

Belich's acid test for a settlement "explosion" is of a doubling in the population of major settler cities within a decade. Many urban centres in the Americas, Australasia and southern Africa experienced that repeatedly.

Explosive colonisation in North America, Australasia and southern Africa was marked by dramatic alternations of boom and bust. It "always ended with a bang, usually a big one", and the third type of colonisation emerged. With economic bust, the colonies' dreams of prodigious independent futures faded, growth slowed, and economies had to be rescued by a new dependence on exports to the "oldlands" of Britain or, for the American West, the urban East. Instead of moving toward independence or equality, the "newlands" – Australia, New Zealand, Southern Africa, the US and Canadian Wests - became more closely tied to the old. The process lasted well into the 20th century: shared collective identities strengthened, along with this economic re-integration.

"Greater Britain", as Belich emphasises, had no formal existence – except briefly as the "White Commonwealth". It was geographically fragmented. But it was economically and culturally integrated through recolonisation to the point where it was virtually a second United States. Decolonisation came only in the mid-20th century, much later than usually thought, with the emergence of real rather than nominal Dominion independence.

Indeed, in some ways it is still in process. Canucks, Aussies and Kiwis still hotly debate their national identities, and how these relate to their British inheritance, to their newer and more diverse migrant populations, and to their surviving indigenous peoples.

The idea of the British World remains on some levels still amorphous. It is open to multiple interpretations, some far more flexible and fertile than others. In some hands, it remains linked with belief in the special virtues of the globalised British. Among historians, Niall Ferguson or Andrew Roberts would be obvious cases in point.

Belich's work is quite free from celebratory chauvinism. As you might guess, he's not an "ethnic Brit", but a New Zealander of Croatian descent. He considers carefully whether other peoples' expansionary settlement patterns might have matched the "Anglo-World" revolution: the French in Algeria, the Chinese in Manchuria, Russians in Siberia, and elsewhere. And he notes that British colonisation was not successful everywhere.

A good half of British and Irish migrants in the 17th and 18th centuries went to the Caribbean, where they died like flies. Ireland, too, could be seen as an instance of mostly failed colonisation. Belich is also far from blind to the history of violence, atrocity, enslavement and even genocide associated with Anglo-World settlerdom – though critics will argue that he gives all these too little space or weight. A "British World" identity may not have survived the end of empire, or might not outlast the potentially-dissolving United Kingdom, but its history will cast long shadows far into any conceivable future.

Stephen Howe is professor of post-colonial history at Bristol University; his books include 'Ireland and Empire'