The Anglosphere, a concept that can trace its lineage back to Winston Churchill’s A History of the English Speaking Peoples, has received renewed interest in the wake of the Brexit referendum.

The idea of the Anglosphere has been advanced in recent times by a number of historians, such as Andrew Roberts (A History of the English Speaking Peoples Since 1900) and Robert Conquest (Reflections on a Ravaged Century), but its most detailed advocate is the American writer on technology and international affairs James C Bennett (The Anglosphere Challenge – Why the English-Speaking Nations Will Lead the Way in the Twenty-First Century).

It is claimed that the unique selling point of the Anglosphere for the UK, post-Brexit, is the possibility to create a new entity which aligns history, culture and politics more closely than EU membership.

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The Anglosphere is generally held to include five core countries: the US, UK, Canada, Australia and New Zealand. However, some Anglosphere advocates broaden membership to include India, and other Commonwealth states such as Singapore.

Advocates suggest that, in the twenty-first century, the Anglosphere is becoming a distinct civilisation in its own right. Their essential argument is that a new world order – based on cultural affinity – is evolving in response to the information revolution, and that those nations best placed to exploit it are those with a strong civil society, most notably the Anglosphere countries.

In addition to these arguments, I would suggest there are five reasons why the Anglosphere could make geostrategic sense for all the core countries. In other words, why realpolitik arguments trump the idea that it is merely a romantic notion.

First is economic exceptionalism. The Anglosphere countries are characterised not just by political freedom, but by stronger economic freedom as well. It is a controversial point, but it can be argued that the Anglosphere economies display economic exceptionalism.

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Second is economic power. The core five Anglosphere economies (the US, UK, Canada, Australia and New Zealand) accounted for 33 per cent of global GDP in 2015 (World Bank data – nominal GDP at market exchange rates). This compared with a 21 per cent share for the EU, excluding the UK. Extending the Anglosphere to include economies such as India and Singapore only raises the proportion to 35 per cent now, but obviously that would change dramatically in the future, given expectations that India will be in the top three economies in the world by 2050.

Third is soft power. Soft power is the ability to influence by attraction and persuasion. The US and the UK rank first and second in the Portland 30 Index of Global Soft Power, but Canada and Australia are also in the top 10. The Anglosphere countries dominate movies, TV, books and news media, helping to forge a shared identity. Anglosphere brands also dominate global commerce, particularly in the information economy.

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Fourth is hard power. The Anglosphere countries tend to spend more money on defence as a proportion of GDP. Recent figures for 2015 estimate defence spending was 3.3 per cent of GDP in the US, 2 per cent of GDP in the UK and 1.9 per cent of GDP in Australia. Higher defence spending, combined with the so-called Five Eyes intelligence sharing alliance, could be seen as providing a basis for enhanced cooperation.

Fifth is the English language. English language usage is in the ascendance. According to the British Council, English is spoken at a useful level by 1.75bn people and this is set to rise to 2bn by 2020. English is likely to be the dominant international language of the twenty-first century, and it is already the lingua franca of academia.