Teams, firms, countries, alliances and families frequently require a sense of who is “us” and who is not. For what part of your extended family do you buy Christmas presents? You own kids – surely. Your nieces and nephews – probably. Your cousin’s children – maybe, maybe not.

Who is “us” when we are paying benefits? Anyone who lives in Britain now? Anyone who has lived in Britain for a sufficiently long period? What about Britons who lived here for many years but now live abroad – should we pay benefits to them? We pay benefits out of a sense of solidarity with fellow members of our society. But where are the boundaries?

What about in eras of political tension? Should we side with the liberal states, where freedom of speech and religion and the peaceful use of property are protected? Or with the democracies, where voting is universal? Or with the capitalist states, where the market is most complete? Or with the secular/Christian/Muslim/[insert religion here] states, our co-religionists?

What about if there were a war? For whom are we prepared to see our taxes spent defending, whether we think they are right or wrong? For whom are we willing to have our soldiers die to protect? What if we had to decide whether to fire nuclear weapons in response to an attack, potentially inviting a nuclear strike on our cities? Who is “us” then? If you live in London, should we fire nukes in response to a nuclear strike on Liverpool, on Glasgow, on Dublin, on Paris, on Washington, on Auckland?

Much discussion assumes that developing a sense of “us” is wholly negative — that its purpose is to divide, to define an out-group that can be ostracised or opposed or even hated. But if the only “us” is the whole of humanity, our engagement with other can only ever be shallow. I cannot buy Christmas presents for all the children in the world. We in Britain cannot pay benefits to every poor person in every country – or at least not do so if providing anything close to the benefits we provide now. If we “side with everyone” in political tension, that really means we’re refusing to stand with or against anyone. If there is no “us” in a war, we will rapidly be over-run by others willing to work as a team.

So it is right and proper to have a sense of “us”. Indeed, every society and every family does so, whether it wants to admit it or not. But what may be less obvious is that the best and most useful sense of “us” evolves through time and circumstance.

So, for example, if you lived in Lithuania in the 13th-14th century, the relevant “us” might have been non-Catholics (pagan or Orthodox) fearing persecution by the Teutonic Knights. But today the “us” for Lithuanians may be Lithuanians, Estonians and Latvians, or perhaps anyone across the EU.

Who is the relevant “us” for Britons today? There was a time when it was anyone loyal to the Empire, then a time anyone opposed to the Bolsheviks, then anyone opposed to the Fascists, then anyone Capitalist, then perhaps anyone committed to democracy and human rights. But who should it be tomorrow?

We’re leaving the EU, separating ourselves from our closest allies, the French and Germans and Dutch and Italians and so forth. Our dear fellow-European friends, who have very much been “us” for decades in the struggle against the Soviet Union, will not be “us” tomorrow.

Who will, if anyone? Americans? In opinion polls, Americans have sometimes been regarded at least as favourably than the most favourably-regarded Europeans. So, for example, in Chatham House’s most recent, 2015 survey, the Dutch and the Swedes (the most-liked Europeans) were regarded especially favourably by 33 and 28 per cent of Britons, respectively, whilst Americans were regarded especially favourably by 33 per cent of Britons. At the peak of the Cold War, from the early 1960s to the early 1980s, America could reasonably have been regarded as Britain’s shield and protector. They were “us”, as our crucial allies against Communism. But over the longer-haul Americans are quite alien to us in many ways. Indeed, fewer Britons declare themselves in favour of free movement with the US than with the EU.

Some “us” are easy. For almost all Britons, all those who live in England and Wales and Scotland are straightforwardly us. Those from Northern Ireland are perhaps, to some, one tiny step out. Then folk from Jersey or Man are a tiny further step. Then one more barely-noticeable step to Falkland Islanders, or those from Gibraltar. Britons working temporarily in the Gulf or Spain or the US are “us”. Those born to Britons living abroad? Again “us”, at least assuming they learn English and come frequently to visit or to work and live.

Then we have those whom Britons see as quasi-ex-pats – the grand-children or great grandchildren or great-great grandchildren of Britons who settled abroad, and those who live in societies dominated by such people who still keep British traditions such as Guy Fawkes, and who have never chosen to rebel against and reject us. Britons regard Canadians and Australians enormously more favourably than even the most favourable of any other significant country — at 44 and 47 per cent, respectively, in 2015. Huge majorities of Britons favour free movement with these countries and New Zealand (more than 3 in favour to every 1 against).

So in truth we already know whom Britons regard as “us”, popularly. Some commentators seem queasy about admitting this, suspecting they will be accused of racism or some such nonsense (as if it could be racist to prefer being “us” with 30 per cent non-European-extraction New Zealanders over more than 99 per cent “white” Poles). It is not racist to be willing to be more deeply engaged with citizens of some countries than others. The alternative is not being deeply engaged with everyone; it is being deeply engaged with no-one. We cannot make “us” universal, but we can make it very narrow if we are unwilling to embrace expanding our sense of “us” because of silly insecurities.

It is good and useful to have a sense of “us”. That is what families and regions and co-religionists and ideological soul-mates and geopolitical allies do all the time. The best “us” can change through time. Currently, Britain’s decision-makers are in a strategic policy flux about who the best “us” should be tomorrow, once we leave the EU. One natural option to consider is the “us” that Britons already embrace — Canadians, Australians and New Zealanders. But there may be better alternatives, and we should not be queasy about debating them. If we are queasy, fearing silly, counterproductive accusations of racism or xenophobia, we risk tomorrow’s “us” becoming narrow and the opportunity to reach out being lost.