Ayatollah Khomeini issued a fatwa to that effect, which was then given effect in the Islamic Republic of Iran, so in the Islamic Republic of Iran, it's flexible enough to allow for sex changes, and it encourages sex changes. But if you want to change your religion in Iran, you've got some serious problems. There are other problems. You're allowed to change sex, but if you want to be a homosexual, theoretically at least, you face the death penalty. Quite how often these penalties are carried out is a moot point, but it's there on the statute books.

The one fatwa that everyone here is probably familiar with is the Salman Rushdie fatwa, but a fatwa doesn't have to be a violent thing at all. A fatwa is simply a ruling on Islamic law; there can be fatwas on clothing.

The first rules about Islamic law weren't even written down for a century and a half after the Prophet's death, and it was another five centuries, half a millennium, before they assumed anything like a definitive form. So there have always been huge arguments over what Islamic law actually requires. There are four main schools of law in Sunni thought and there's a separate school of law in Shia thought, so these arguments do take place.

People are coupling and decoupling all the time in Great Britain. The fact that Muslims choose to precede it with a certain formula of words, shouldn't bar them from anything. But, no one's saying that polygamy should be institutionalized in this country. That Muslim's uniquely should be allowed to have two or three or four marriages.

The Muslim Arbitration Tribunal, if you look at its website, it basically deals with commercial disputes, it's not allowed to deal with matters involving children, it's not allowed to deal with criminal matters, it's subject to judicial review, it's subject to the Human Rights Act, it's subject to the Children's Act, and it's completely proper and right that it should be subject to all those things.

There have been lots and lots of fatwas against violence. But it is an interesting question. A Mufti is the person that issues the fatwa and you'll find Muftis at all the Madrasas. Basically once you've studied for long enough you have the authority to issue a fatwa. But there are limits. I can bang on and on on the point but all I'm really saying is that there isn't a simple answer.

I spoke to my father - my father's from Pakistan and he's also a lawyer - I said to him, "Well what does the Shari'a say?" And he said, "Well, of course it doesn't justify suicide bombs," but he didn't seem to know where the Shari'a came from or what it was all about. The more I asked people in my family as well as friends, the more I realized that there seemed to be widespread ignorance in the Muslim community. And that's something which I actually found to be the case over the next two and a half, three years I spent writing the book.