Identity is a complex and shifting subject. We variously identify ourselves by nationality, ethnicity, sexuality, beliefs, habits, professions, residence. Sometimes these overlapping identities are strongest when they feel beleaguered, when we feel that an aspect of our identity is threatened, when we are on the defensive.

London is hardly a defensive identity. Rarely have Londoners shared a sense that they might be swallowed by something bigger, except perhaps in times of war. It was often the reverse: as an imperial, Commonwealth or global capital, the city has been a source of power for centuries and has a well-documented history of attracting people to live there from the rest of the country and abroad.

London ancestry was never an essential qualification for identity as a Londoner, but London today is more mixed than ever. Long-term migration seems to have intensified in the past four decades – as it often does in phases of growth. Today a majority of adults were born outside the city.

Higher levels of migration, however, do not mean that people who live in London have a weaker connection to their city. Despite demographic change, Londoners today are as likely to consider themselves to be Londoners as they were 40 years ago. And far from being the preserve of some groups, the London identity seems widely shared across generations, social classes and ethnic groups, certainly more than the British, English or European identity.

So the London identity, it seems, is relatively easy to adopt. The identity of such a dominant and diverse city has to be malleable and composite – some Londoners are Cockney, some are queer Londoners, Black Londoners, Jewish Londoners, South Londoners. But we know very little about where London sits among the jigsaw pieces of identity. We see that identities become strongest when they are protective – against ethnic, religious, gender, sexual or even ‘postcode’ prejudice. Yet we don’t know whether the London identity alone can be protective too, or if it can offer a sense of rootedness and self-esteem to those who need it. The data on urban identities is meagre. When polled, people may say they are definitely Londoners, but the extent to which they can relate to others in their city is still unknown.

Other cities, like New York, have managed to forge a strong identity based on their heritage of immigration, and some argue that London might be doing the same. London’s three mayors to date have been keen to stress the city’s acceptance of difference, in celebratory moments as well as in tough times.

London is certainly diverse, but some would suggest the city is divided too; it has always been a place of higher inequality, and its sheer size enables Londoners to interact with people who are more like them. But integration and interaction come in many different forms: it is hard to see how London could function without its down-to-earth approach to mixing – the small, often convivial interactions in shops, in the office or at the school gates – and the shared appreciation of the city’s identifiers – such as green spaces and landmarks.

At a time when policymakers are eager to find ways to bring people together, we should be taking a closer look at how identity can support social cohesion in the capital; and how an appropriate and positive overarching London identity could bridge other social divides.

This piece is informed by a new Centre for London paper that reviews the evidence on how London identities have changed, and what Londoners share in