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.

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.

There were periods in Islamic history when things like apostasy and blasphemy were made punishable. So you know it kind of depends - there's no argument, quite apart from the question of the divine or otherwise nature of the Qur'an, that huge swathes of Islamic law are man-made. Clerics here - in maintaining their power, will often try to elide that and say "Well no, actually this isn't man-made at all. Stoning is part of the divine revelation." It isn't in the Qur'an but the way this has been done over the years is to take the Hadith.

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.

I realized that the ignorance was profound. I don't mean that in a pejorative sense, it's just that people didn't know what the Shari'a was, as such. They knew that it was something good. I should say perhaps that the Shari'a, etymologically in Arabic, means a desert path to water. It means a path towards salvation, in the seventh-century context, to the desert people. If you have a path to water, that's the path you want to take to get you where you want to get to; where you should get to. And that much was clear but beyond that people didn't know what the rules were.

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.

If Muslims want to take their disputes to religious arbitrators because they genuinely believe that it's a matter of great spiritual importance that they do that, they shouldn't be the only community in this country that's denied the opportunity to do that. Because the Jewish population has been entitled to take their disputes to tribunals known as the Beth Din for over one hundred years, and the Church of England is integrated into the fabric of this country, and there are ecclesiastical tribunals where religious disputes can be dealt with.