I didn't quite know whether I was writing for the non-Muslim or the Muslim, and at the end of the day I'm writing, I hope, for people who are interested, whatever their faith. Even if they don't have any faith. As a barrister I had certain advantages - I could think like a lawyer and I knew how all the laws were fitted together and all the rest of it. One of the things I realized pretty early on while I was writing book about Shari'a was that that was as much a hinderance as it was a help because the Shari'a isn't just a system of rules.

I think there's a real danger that Islamophobia can actually be a cover for something far more malign. I don't want to sound like a spokesman for the Muslim Arbitration Tribunal but I am a supporter of autonomy for religious communities and for non-discrimination.

There's crucial distinction that has to be drawn between the Shari'a, which is this hugely expansive vision of cosmic order that I've been describing, and principles of Islamic law, known in Arabic as "Fiqh" - a word that means understanding. If you're a devout Muslim, you don't argue against the Shari'a; the Shari'a is the path that God has laid down. But what you can do, and what people are doing all the time, is arguing over the correct interpretation of the Shari'a, arguing over the Fiqh. That's something that has been going on throughout Islamic history.

One of things that surprised me when I was in Iran was to find out that the country finances seven times as many sex change operations as the entire European Union. And the reason for that is because Ayatollah Khomeini himself, in the early 1960s, in the same time that he was developing this other idea of an Islamic state, also hit upon the idea that if a person is born into the wrong sex, it was entirely proper for them to change sex.

I think it's important to understand Shari'a to be rooted in history - what we know about the history and what we don't know about the history. So then, if people want to argue, at least they're arguing from the same point and we know what we know, and we know what we don't know.

In 1979, you had the revolution in Iran. You had the Hudood Ordinances in Pakistan, which are the laws that are notoriously used against women, which are theoretically used against thieves although they're never carried out - an actual amputation or an actual stoning. The blasphemy laws, again, never actually carried out, though they're there, heavy with menace on the statute books.

Whenever one writes a book one should have a notional reader in mind.