When I sat down to start work on this novel, my ambition for it could be simply put. I wanted to write a Big Fat London Novel.
In the first instance, my inspiration was a remark made by my wife. One day, she said something like, "You know, there's something that would have interested Dickens about the state of London today." That remark is easier to understand – I immediately got what it meant – than it is to explain, but it got me thinking about the possibility of writing a long realist novel about contemporary London. I think there are two particular points of similarity between the London of today and that of the 19th century. One is that today's levels of inequality are measurably similar to those of Victorian England; extremes of wealth and poverty, of good and bad luck and of good and bad behaviour are visible wherever you look in our capital city. Second, just as in Victorian England, London is where people now come to make their fortunes. Where once it was Dick Whittington, now it attracts Polish builders, plumbers and cleaners, Czech nannies, French bond dealers and Russian dentists – and those are just people who are personally known to me. The city seems to contain every possible combination of person, origin, profession and ambition.
All this added up to the idea that London is a place that has undergone convulsive change, all the more marked because it has been continual. I grew up abroad and when I first passed through London in the 1970s, it seemed a drab and provincial place. The other big thing about it was that it was grey: the sky was grey, the buildings were grey, the people were grey, the mood was grey. The food was especially grey. Nobody could now think that about the city: London is a place of immense, sometimes overwhelming variety, colour and energy, and with an edge of anger never far away. When I first travelled to New York, in 1982, on a summer holiday as a student, I remember thinking how exciting it was, how energising it felt, and also how it felt dangerous – it was a place where you could make a wrong turn, either geographically or just in a human interaction, and suddenly find yourself in trouble. Now, whenever I return to London after having been away, I have that same feeling. It's an exciting place, but it doesn't always feel like a safe one.
In addition, London has become a world city. Today, even more than when it was the capital of a global empire, the whole world presses on London and is present in it. A few years ago I got talking to a Polish woman who had a PhD in child psychology but was working as a cleaner and nanny. She told me about her reasons for being here; she recited various practical motives and then her face changed and she said, "And of course, there is now also something you could call the London dream." There was an extraordinarily vivid wistfulness and longing in her voice, which gave me a sense that London is now a place that people from all over the world come to with the idea of pursuing and fulfilling their dreams. We're used to the idea that the US is that place, and feel less comfortable about our home now playing that role, too.
So I started to think about my Big Fat London Novel, which I was by now calling Capital, and how to weave all these themes into it, and I began to work on it in my usual way, which is to wander about aimlessly and look out of the window and generally faff about. I wanted the novel to feel like London feels to me, and many aesthetic choices followed from that fact. It had to feel, if not crowded, then thoroughly populated; its characters had to be from a wide range of backgrounds and homelands; and it had to be set in one particular street, because the geographical unit of city life is the street. I wanted it to reflect the sense of a city in change and flux, at a peak moment of obliviousness. When I began the book, in early 2006, I was sure that a crash was coming: I wasn't sure what form it would take, and I certainly didn't know it was going to be as structural, systematic and globally all-encompassing as it has turned out to be. But I wanted the book to begin with the reader knowing something that the characters don't: that this moment in 2007 to 2008 is the peak of a bubble. It's a curious thing to say about a book set in such a recent past, but Capital was intended to be a historical novel. The main thing that has changed between then and now – while everything looks the same – is the inside of people's heads, and that is the most profound kind of change there is.
• John Lanchester will be talking to John Mullan about Capital at 7pm on Monday 18 March at Kings Place, London N1. theguardian.com/books/series/bookclub
