London is at once a geographical entity and an identity. Physically, its extent is pretty clear: 32 boroughs and the City of London, more or less bounded by a 117-mile motorway and a green belt. Even if you define the geography of the capital differently – as the Greater London Urban Area, the London Travel To Work Area, or the districts with an 020 telephone prefix – London remains pretty clearly bounded, a place of geographical and political integrity.

But London is more than an area that can be charted on a map: it has a prevailing spirit. The capital of a country that voted for Brexit, it is arguably the world’s most global city. Its inner boroughs contain the most affluent area not merely in Britain, but in Europe. The average age of the population is younger than in the rest of the UK, at 33. Some 40 per cent of its population have a degree (compared, for example, to just over 25 per cent in northeast England). Less than 30 per cent of its citizens identify as white British.

This anomalousness has led some (the FT’s Philip Stephens and the Guardian’s Aditya Chakrabortty among them) to float the possibility of a separatist city-state. A London liberated from national shackles would have twice the GDP of Singapore, a higher population than Austria, and, at current levels, more than six times as many tourists as Brazil.

However, London’s peculiarities lead it to break the bounds of geography as much they insulate it. Where would London separatism leave Brighton, or Cambridge, for example – towns with their own distinctive histories and atmospheres, which nevertheless share many of London’s values and characteristics (including high house prices)? The writer Jeremy Cliffe has gone so far as to argue that London-places should include towns as far afield as Swindon and Warrington, seeing in London an indication of what the UK might eventually become: a land of geographically-spread pockets of ethnic diversity, relative openness and social liberalism. In this version of the future, the values of the young will come to predominate, and Londoners, including immigrants, will move out of the capital, spreading London values as they go.

This perhaps looks less improbable following the June 2017 election; until then, it was widely assumed that an ageing population would lead nationally to more conservatism. (The likelihood of voting Conservative rises by 8 per cent for every 10 years of ageing.) So when we think about London’s future, what are we thinking about? What is it about the city, or its values, that we want to preserve, and perhaps spread more widely? If London is animated by something – a mood, a set of values, a way of going about things – what are its key ingredients?

We asked a range of people interested in London to describe what sets it apart from other cities, and what they see as being the greatest challenges in planning its future.

Lorna Lee

Head of Cultural and Heritage Services, London Borough of Waltham Forest

London’s long and varied history has led to the development of a rich mix and vibrancy of communities. It is very much a contemporary city, a city of innovation and ideas, with its creative ecology making it a global centre across the whole spectrum of arts and cultural industries.

It has developed as a place of sanctuary and migration, and it continues today as a city of continual change, where incredibly diverse communities live and work together – unlike cities such as Paris, where different communities have become isolated in ghettoes away from the seemingly liberal city centre. But affordability and the rising cost of living, particularly of housing, is a big challenge. And with high property prices affecting the availability of suitable space for business, there is particular concern about the limited affordable workspace for creative enterprise.

We need to avoid a division of society into the haves and have-nots. Art and culture have a strong part to play here, creating a sense of ownership, civic pride, and belonging, and we must strive to put culture at the heart of London’s continued development.

Daniel Raven-Ellison

Coordinator of the Greater London National Park City Initiative

London is well known as a political, cultural and financial centre, but in many ways it is an ecological centre too. For 2,000 years, a mixture of top-down policy and grassroots action has led to the capital being the most ecologically diverse region of the UK, and one of the world’s physically greenest cities. From the Natural History Museum to Kew Gardens and Barnes Wetlands Centre, London arguably also has the world’s greatest density of world-class environmental institutions.

That said, cars are prioritised over space for children to play together, housing is too expensive, and new developments are increasingly encroaching on the green spaces that contribute to London’s being such a great city. The effects include childhood development being stunted, talent bleeding out of the city, and the disappearance of places where we can enjoy being lost. We need radical and brave action to rebalance our communities so that they can thrive.

Victoria Wägner

Projects Director at urban design firm Publica

London’s diversity is its greatest asset, found not only in London’s multicultural population but also in the city’s complex mix of land uses and diverse urban make-up. These give London a unique resilience to deal with change and an extraordinary capacity to reinvent itself by adapting and regenerating from within. Throughout its history, London’s high-quality building stock has been continuously reappropriated, resulting in an intensity of use that is quintessentially London.

London’s survival as a thriving city depends on our ability to address both the housing crisis and the impact of rising land values on the city’s creative industries. With the incremental loss of affordability, we risk losing the diversity and vibrancy that makes London what it is.

The London we know has been flexible and open enough to absorb change. It is essential that we maintain that resilience. This means ensuring that all Londoners have access to affordable housing, and that the creative industries – which are at the heart of London’s identity and economy – can continue to have a place in the city. Otherwise, we risk losing precisely what gives London its identity, its competitive edge, and its ability to lead in the 21st century.

Laura Mazzeo

Managing Partner at Farrells architecture and urban design firm

London feels like home to all of us non-UK citizens. Our difference is seen as a positive here. I have lived in Hong Kong and Paris, and visited San Francisco, New York, Sydney, Shanghai, and Tokyo. None made me so welcome that I wanted to stay forever; London did and still does. But as the managing partner of a global design practice with 100 staff – the majority of whom are from the EU – the lack of openness and inclusiveness promoted by current British politics is of real concern.

Sybil Kapoor

Award-winning food and travel writer, author of Modern British Food

London is unique in that it allows everyone to be themselves. There is no pressure to conform to an identity, unlike in other cities, such as Paris or New York. In fact, the only real pressure on Londoners is to be tolerant of others. The biggest issue the capital faces in the near future is balancing sustainability with profit. London is founded on making money, and, unfortunately, this can lead to exploitation in many forms – from alienating city architecture and little affordable housing to poor air quality and a lack of green spaces. Yet London has the potential to be a cutting-edge green city.

Darryl Chen

Partner at Hawkins Brown Architects

As I have travelled around the world, the thing I have noticed most about London is the sheer number of checks and balances on doing anything in the city, so that things are done with a level of rigour and critical scrutiny that I don’t believe exists anywhere else in the world. That, along with Londoners’ tolerance, is born out of so many people sharing too little space. From our tiny tube carriages to the rabbit hutches we live in, this sheer proximity creates an urban intensity that is both frustrating and liberating.

What concerns me most about this city’s future? We desperately need better checks and balances on the sale of land, the occupation of buildings and the form of new development to ensure that London stays diverse, attractive and innovative.

Caroline Artis

London Senior Partner at EY

Most major world cities have one or two great attributes, such as a great financial services centre, world-class universities, or a highly educated and diverse workforce. But London is the only one that has it all.

Add to that a fantastic history, culture and nightlife, and you can see why London stands out. To retain this reputation, London must strive to demonstrate that it remains a global city. This will require better infrastructure, such as new airports or runways, and rail links like Crossrail 2 – as well as world-class broadband and communications.

Finn Williams

Regeneration Manager, Greater London Authority, and Centre for London Associate

You can tell a lot about a city by listening to the music that comes out of it. London has invented Punk, Jungle and Grime. It’s the edge you can hear in this music that makes London more mixed, unpredictable, and exhilarating than anywhere else I know.

The beauty of London is that it can’t be defined as one preconceived idea or a single place. It’s built up from so many different towns, cultures and economies that no one boundary or statistic can accurately represent the reality of what London is today. When we plan London, we need to remember that London is a different place to every Londoner.

One of the key challenges of planning London’s future is going to be understanding what it is to be a capital at a time when city-states seem to be superseding nation states. If most Londoners probably now have more in common with people from New York than they do with people from York, what should our wider responsibilities be beyond London?

Olia Hercules

London-based chef and author of award-winning cookbook Mamushka: Recipes from Ukraine

I cannot think of a more cosmopolitan city than London; even New York seems less so. What I love about the city is that it has an inherent capability to recognise passion and hard work, and to value diversity. I have no family in the UK, but I’ve found people who have become like family. They have been crucial in helping me, a working single mother, to achieve what I have. London is the place where my son was born and where my lifetime friendships have been made, so I cannot imagine living anywhere else. The things that concern me most about the future of London are Brexit, populism and misinformation.

Tristram Stuart

Founder of food waste charity Feedback

Where London is, and why, has largely been forgotten. It was originally situated in the Thames Valley because this was a fantastic place to grow food and thus settle a sizeable population. If we tapped into the incredible wealth of food grown within 100 miles of our city, it would feed us well and help build sustainable businesses in our rural hinterland. Our ecological footprint needs to shrink massively and there’s no way more delicious to do that than changing our diets, as well as eating and wasting less.

Tony Halmos

Director of the King’s Commission on London and Visiting Professor at The Policy Institute, King’s College London

London is very different from other major world cities in a number of ways: it is a centre for government, commerce, culture, media and sport; it is uniquely located in world time zones to do international business with Asia in the morning and the Americas in the afternoon; and its language, English, is the language of world business. This helps make it one of the world’s leading international finance and business centres. The single most immediate issue facing London is making sure that it has the most successful Brexit negotiations possible, so that London can continue to thrive through its trading arrangements with Europe. It must also maintain its ability to attract the skilled workers it needs, as well as its overall international standing.