CANZUK is a proposal for a new trade, migration and security partnership between Canada, Australia, NZ and the UK.

Kiwis and Aussies like to joke about each other, but remain close mates, right?

As countries, that closeness is reflected in two big agreements: the Australia - New Zealand Closer Economic Relations Trade Agreement (ANZCERTA); and the trans-Tasman Travel Arrangement (TTTA). These agreements allow Aussies and Kiwis to travel and work freely in each others' countries, and allows businesses to sell their products almost as easily as if they were selling them at home.

But wouldn't it be great if the same applied to Kiwis dealing with, or travelling to Canada or the United Kingdom?

A couple of weeks back, the Canadian Conservative Party (the main opposition party in Canada) held its annual convention. There it adopted (by 99 per cent to 1 per cent) a policy Canadians call CANZUK.

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CANZUK is a proposal for a new trade, migration and security partnership between Canada, Australia, New Zealand and the United Kingdom - hence 'CANZUK'.

There are Australian politicians who are fans of this too. Aussie Senator James Paterson has proposed that ANZCERTA and the TTTA be extended to include Canada and the UK.

So a New Zealander would be able to travel freely anywhere in Canada and the UK, as well as Australia, and Kiwi businesses could sell to Canada and the UK on the same basis they currently sell to Australia.

There is already a security partnership in place, called the "Five Eyes" agreement, between the CANZUK countries and the United States. The partnership would build on that for the CANZUK countries in particular.

A geopolitical partnership like this would have lots of practical everyday value, but it would also be a big deal in international terms.

Together these countries would have a GDP of nearly NZ$9 trillion (about half the GDP of China), making it the fourth largest economic bloc in the world. Together, they'd also have more than 70 per cent of the strength of the US — by a large margin the second global power. The land area covered would be the largest of any political grouping.

The CANZUK countries have a natural fit, in a way that almost no other large international grouping does.

We see the tensions Canada and the US are having over the North American Free Trade Agreement (NAFTA), and the difference in their values over issues such as the treatment of immigrants or the environment. We see the UK currently leaving the European Union because it cannot continue down the EU's path of building a Single European State.

The CANZUK countries, by contrast, have huge mutual regard.

These are also countries with very similar legal and political traditions, allowing businesses to understand what they're dealing with and making it straightforward to recognise each other's rules. Even the political parties divide along lines that make sense to most citizens. We watch each others' movies, TV dramas, comedies, even reality TV shows, and we recognise ourselves in what the others do.

Each country has its own important particular issues to be respected, of course - the autonomy of Scotland in the UK or Quebec in Canada, continued work of reconciliation with the First Nations in Canada, Aboriginal Australians or Māoris in NZ.

But by working together, reflecting their natural affinities, the CANZUK countries could present a common face to the world on a range of issues, including environmental action, the rules of the Internet, financial regulation, and international property rights. They can collaborate in areas such as space, cultural exchange, patent law, emergency assistance and many others.

The New Zealand Government's Coalition Agreement includes a commitment to "Closer Commonwealth Economic Relations". That means adding Canada and the UK (and perhaps eventually South African as well) to ANZCERTA and the TTA.

Some of the big Canadian players and Aussies are on board. Now if we can just get the British to join in wholeheartedly, we'll be on. Let's make it happen together!

Andrew Lilico is an economist and politics writer who lives in London, but remembers he is a New Zealander.