Hearts and Minds began in 2001, when I noticed just how many people in my daily life were immigrants. The man who swept the streets, the woman who cleaned my house, the waitresses in a local cafe, the dry cleaner, the firm of minicab drivers, builders – all were legal or illegal immigrants. How did they adapt? How had they arrived here? Were they homesick, happy, enterprising or despondent?

Other people noticed this, too, and a number of newspaper articles and books came out on the subject of “bloody foreigners”, immigrants and asylum seekers. I was writing Hearts and Minds long before the publication of Marina Lewycka’s A Short History of Tractors in Ukrainian, Rose Tremain’s The Road Home ; or Kate Clanchy’s What is She Doing Here? It was supposed to be published in 2004. What delayed it was getting seriously ill with, among other things, cancer. All my operations were performed by first or second generation immigrants, and in hospital I was nursed by women from all over the world. When I came out of hospital I was for a time wholly dependent on a succession of au pairs from Eastern Europe. These women had fascinating stories to tell of war, ambition, misery or triumph over adversity.

Unlike Polly Noble in my novel, I am in a happy marriage, and able to work from home, but my domestic life felt, like hers, increasingly penetrated by the wretched of many nations as they fled from war, famine and economic destitution. I often encountered au pairs on the run from people not unlike the pimps Sergei and Dmitri. My curiosity led me to interview teenage prostitutes, minicab drivers, teachers, policemen, human rights lawyers, expert witnesses, doctors, torture victims and so on. However, I did not want to write only about the immigrant underclass, because I know many professional people who are also from other countries and cultures. Gradually, my five main characters emerged as distinct personalities, meeting and parting, glimpsing each other (as Polly almost runs over Ian on his bicycle, unknowingly, during the school run) and eventually saving each other’s lives. My material was unmanageable until I made every chapter no more than 3,000 words long; each tells the story from the character’s point of view; and each is told in the historic present. I often use the historic present in journalism, and didn’t realise what a difficult tense it is to use in fiction.

One of the many other problems I faced was that, because of my long delay, real life kept catching up with my plot. For instance, it was obvious that, after 9/11, London would suffer a terrorist attack next. I had my bomber blow up a Tube train at King’s Cross…and then 7/7 happened. It was only when I met someone from MI5 who told me how many bomb attempts have been foiled that I found one of the climaxes to the story…and then the de Menezes shooting happened.

The most important story of all to me in this book is that of Anna. Through charities such as Women For Women, which helps the survivors of war rebuild their lives, I have met a number of women who were raped, trafficked and prostituted. It was also not difficult at the time of writing to find teenage prostitutes and addicts around King’s Cross and St Pancras international railway station, and if you pay them for their time they’ll tell you about their work. A month after my novel was completed, Agar Grove suddenly became a favourite place for young prostitutes, like Anna in being around fifteen.

Polly’s burglary was described a few months before an actual burglary (which I described in The Independentin 2007) took place in our house, when my husband and I had a terrifying encounter a young thug one Sunday afternoon in order to prevent him running off with my laptop (containing Hearts and Minds). We were lucky that neither we, nor our son, were knifed in the process, because he turned out to be all too well known to the police, and it was partly because we fought back that they were able to catch and imprison him. I write about what I imagine or know – sometimes before that happens.