Dr Julian Lewis: I thank the Secretary of State for the way in which he is introducing the debate. The question about other countries possessing nuclear weapons takes me back to the old arguments where we used to ask people to name a single country that would either acquire nuclear weapons because we had got them, or get rid of them if we decided unilaterally to get rid of ours. Do you know what? They never came up with the name of one country.

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[Ronnie Cowan: [ ... ] The majority of supporters of WMD [weapons of mass destruction] are just like me with one vital difference. They believe that WMD are a deterrent. They believe their existence has kept us safe. As those weapons have existed during a period in which we have avoided wars on the scale of the first and second world wars, I can see where they are coming from. If people believe that keeping their guard up is keeping them safe, then lowering their guard is a frightening thing to do. In this case, they are so frightened that they are prepared to carry out the greatest atrocity humankind has ever perpetrated, and have it done in their name. Well, not in my name. Not all countries believe that nuclear warfare is required. Maybe as many as nine countries feel the need to have nuclear weapons, out of 200.]

Dr Lewis: I make one point for the hon. Gentleman’s consideration – one could say exactly the same thing about poison gas, which was used in the first world war and not in the second. It was not used in the second because of fear of overwhelming retaliation. The British warned that we had those stocks and that ​we would retaliate not only on our own behalf but on behalf of our allies such as Russia. The question is, which keeps the peace?

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Dr Lewis: Let me try this question again. If we were to give up our nuclear weapons, which other countries that possess nuclear weapons would follow suit? Does the hon. Lady know how many nuclear warheads have been reduced as a result of us reducing our nuclear warhead totals unilaterally? The answer is a big fat zero.

[Caroline Lucas: That is why one needs international processes such as the UN treaty that I have described, which is supported by 122 countries, in order to make that happen. Although I am personally in favour of unilateral nuclear disarmament, that is not the case that I am making this afternoon. I am moving one step towards people such as hon. Members like himself – or right hon. Members like himself, perhaps, I cannot really remember – who I completely understand are never going to be persuaded by unilateral nuclear disarmament, but who I hope might be willing to engage in a serious argument about multilateral nuclear disarmament. ... ]

 [For Julian's speech in this debate click here.]