Close up, I saw a truly frightening level of isolation, fear and despair. But I also heard touching love stories, saw the happiness of children placed above everything else, and an extraordinary resilience drawn from faith. Through these women, I met others, whose husbands were detained in Belmarsh prison under suspicion of terrorism – but with no charges brought. After their husbands' arrests, these women were abruptly isolated, even within their own communities. Their children's futures became unpredictable; the children themselves were scarred by confusion, fear, and – the older ones, sometimes – hatred. Under the pressure of incarceration (or, later, under house arrest), their husbands changed personality; they were gripped by paranoia; several went on hunger strike or tried to commit suicide; many remain on heavy medication.
Two summers ago, after the first reading of my play about these women's lives, one of the actors sent me a text message. She said that whenever she saw a veiled woman on the bus she thought of Sabah, the woman whose part she had read and whose life she now couldn't get out of her mind. This weekend, Juliet Stevenson will play Sabah, one of eight Muslim women whose lives have been translated into verbatim musical theatre.
It was Vanessa Redgrave's idea to make it musical. She read the script and said: "It should be an opera." But the idea terrified me: I wanted to keep the precision and detail of the text. I disregarded the idea until I met the composer Jessica Dannheisser, and heard her use a mixture of sung and spoken text in a performance of poetry and music for Palestine at Cadogan Hall. Maybe it would work, if she would take my play on. She did. Then her friend, the director Poppy Burton-Morgan, persuaded me to drop some characters, and miraculously produced the libretto for two singers.
Some of my favourite actors – Gemma Jones, Manjinder Virk, Harriet Ladbury and Diana Hardcastle – came on board. Then came the cellist, Oliver Coates, the soprano Anna Dennis, and the mezzo-soprano Carole Wilson. A total of eight performers – three of them seen in short film sequences – play women from cultures as varied as those of Senegal, France, Jordan, Palestine, India and the English Midlands. In previous lives, some had been basketball stars, or teachers; some have degrees in business administration or economics. Others came from households where they were not involved in many family decisions.
Like all verbatim plays, the truth of this one – which I called Waiting – depends on using only the actual words of actual people. These words have mainly been collected from many lengthy conversations, some of them translated from Arabic by the children, some of them taped interviews.
All of these women came to Britain as refugees, or married refugees here. All had found Britain an oasis of safety; for many of them, their lives were in sharp contrast to the years of prison or torture previously suffered by their husbands. But 9/11 ended their idyll. Foreign men were arrested in droves for American cash bounties in Pakistan and Afghanistan – or on a business trip in Gambia, in the case of Sabah's husband - and sent to Guantánamo. In Britain, on 19 December 2001, a dozen foreign Muslim men were interned without trial in Belmarsh prison. Their wives had no means of knowing what had happened to their husbands and why.
I never planned to write about my friends: privacy was extremely important to them. Only once or twice, when they specifically asked me to, did I write articles about them. But when I began to think about Waiting, it was as a joint project, a telling of life stories. When they come to London's South Bank to see the play this weekend, it will be as much to hear each other's stories as to see their own presented.
Each of these women have so much in common; each has been changed forever by their experience of Britain. Their own words put it most powerfully. One said: "I can't remember happiness." Another woman recalled going to the zoo with her daughter's class. "She was so happy, so excited, running to see animals she'd never seen, like the giraffes," she told me. "I was smiling for her, but inside I was only thinking of those cages, and my husband in his cage." For some, things have gone from bad to worse, and then worse again. "Nobody can see my heart. This time will stay in my heart forever ... I must forget. I must forgive."
• After each show there will be a discussion including Salma Yaqoob, Helena Kennedy QC, Gareth Peirce, Manjinder Virk, Riz Ahmed, and Moazzam Begg.