Dr Julian Lewis: I sometimes think that the hon. Member for Islington North (Jeremy Corbyn) and I missed our profession. We have both been arguing the merits and demerits of nuclear weapons and nuclear deterrence – I would like to think passionately but also reasonably – for at least the last 30 years. Perhaps we should cast ourselves as the nuclear version of “Les Misérables”, but which one of us would be the fugitive and which one the pursuer is a matter for others to decide. Certainly, I would like to think that our relationship is a bit more positive, if adversarial, than that of Jean Valjean and his nemesis, but the fact is that we do disagree, and we represent two diametrically opposed schools of thought. I genuinely congratulate him on securing this debate. I was away with the Intelligence and Security Committee in the United States when he applied for it. Had I not been, I would have been happy to support him in applying for it, just as he supported me very fully earlier this year when I applied for the debate that we both secured on Trident, which most people thought was beneficial and extremely valuable, whichever side of the debate they happened to support.

Jeremy Corbyn: I thank the hon. Gentleman for that, and inform him that I prayed in aid his undoubted wish to have this debate in order to continue our lifelong struggle for nuclear peace.

Dr Lewis: I am delighted to hear that, and that is what I hoped he would do. I will try to follow the chain of the hon. Gentleman’s argument – not too pedantically, I hope. I will start where he did, in 1945, because as he said, that was the one occasion on which nuclear weapons were used. However, it all depends on what we mean by the verb “to use”, because although they were used, very controversially, to end the war with Japan, I contend that they have been used frequently, indeed continuously, ever since. Once we get to the stage of mutual nuclear deterrence, the use of the nuclear deterrent lies not in firing it, but in possessing it, so that no one else will ever be tempted to do to a country what America was able to do to Japan. Whether we regard that as right or wrong in the circumstances is irrelevant. We want to ensure that no one is tempted to do that again in the future. The use of the nuclear deterrent is to deter anyone from attacking a country with mass destruction weapons.

Towards the end of the hon. Gentleman’s speech, he said that nuclear weapons were a fat lot of use as far as 9/11 was concerned. That is an update of an argument that we used to hear in the 1980s, when it was said, “Well, your nuclear deterrent didn’t stop Argentina invading the Falklands, did it?” My answer to the more modern version of that has to be the same as my answer to the earlier version: if a weapons system does not deter every sort of threat – and it does deter some dangerous threats – there is no more reason to get rid of it than to get rid of the antidote to a deadly disease just because it could not cure us of other, unrelated diseases.

The question of nuclear deterrence was substantially worked out before nuclear weapons made their existence known. In 1944-45, the British Chiefs of Staff commissioned a study by defence scientists under a famous professor, Sir Henry Tizard, to try to imagine what the future nature of warfare would be once Germany and Japan were defeated. Tizard was not allowed to go into the question of nuclear weapons, even though he knew that they were under development, but he could not resist putting in his report, in 1945, that he and his fellow senior defence scientists could see only one answer to the atomic bomb, if indeed it was developed. He said:

“A knowledge that we were prepared, in the last resort”

to retaliate with such a weapon

“might well deter an aggressive nation. Duelling was a recognised method of settling quarrels between men of high social standing so long as the duellists stood 20 paces apart and fired at each other with pistols of a primitive type. If the rule had been that they should stand a yard apart with pistols at each other’s hearts, we doubt whether it would long have remained a recognised method of settling affairs of honour.”

The hon. Member for Islington North said that Nazi scientists played a great part in the subsequent development of nuclear weapons. I do not think that that is quite true. The Nazis went down a blind alley as far as nuclear weapons development was concerned. They were subject to eavesdropping at Farm Hall, where intelligence experts heard them doubting and wondering whether it was true that the Americans had successfully developed the atomic bomb used in Japan. However, he is absolutely right that Nazi scientists played a key role in developing the rocketry that could carry such weapons to their destination, should they ever be fired. As I like to stress over and over, that is not what their use consists of, once the stage of stable nuclear deterrence is reached.

Similarly and interestingly, the hon. Gentleman said, again rightly, that the Cuban missile crisis was probably the most dangerous point in the cold war – the point when the possibility of a nuclear exchange was at its highest. The concession that the Americans made was even a little greater than he suggested, because they had nuclear-armed missiles based in Turkey. It was not a question of targeting Turkey; the US had missiles based in Turkey, which Kennedy wisely decided the US should offer to remove as a way of giving Khrushchev some face-saving ability, so it would not look too much like a straightforward climb-down for him to remove the Soviet missiles from Cuba.

Although the hon. Gentleman talked a great deal about non-proliferation, he did not quote from the relevant article in the non-proliferation treaty, which is often quoted incompletely. The preamble to the treaty states that nuclear disarmament should occur

“pursuant to” –

that is, in conformity with –

“a treaty on general and complete disarmament”:

in other words, worldwide conventional disarmament.

Article VI of the non-proliferation treaty states in full:

“Each of the parties to the treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.”

There are three elements to article VI: the cessation of the nuclear arms race at an early date, a world free of nuclear weapons, and a world with general disarmament. On the first, Britain has never been part of the nuclear arms race. It is true that the superpowers have: they piled up nuclear weapons on both sides of the iron curtain.

The one thing on which I always used to agree with the famous former general secretary of the Campaign for Nuclear Disarmament, Monsignor Bruce Kent, was his view that the Americans and the Russians could each unilaterally cut their nuclear arsenals by 10% without any loss of security whatsoever. I agreed entirely: both sides had massive overkill capability. However, Britain never did. For that matter, China never has, and nor has France. We in this country have always followed a policy of minimum strategic nuclear deterrence. In other words, it does not matter if another country has the ability to wipe us out 50 times over, because we can cause unacceptable levels of devastation in retaliation, which is why the other country will not do it in the first place.

The hon. Gentleman – I nearly called him my hon. Friend, because I regard him as an honourable friend – asked rhetorically which country had greater moral standing in the world: South Africa, for renouncing its programme, or the United Kingdom. I suppose it depends on one’s standard of morality and how one measures it. I would say that it is a little like arguing that the neutral countries in 1940 – for instance, Holland, Belgium and Norway – had greater moral standing than democracies such as Britain and France, which at least tried to have armaments with which to defend themselves. However, that is not my standard of morality or my way of measuring it. My way of measuring it is to ask which country, by adopting a particular policy, will do most to prevent a nuclear war from breaking out. It was implicit – at one point, it was virtually explicit – in some of the hon. Gentleman’s remarks that he accepts that both of us share the same end. We do not wish a nuclear war to happen; we just disagree as much as it is possible to disagree on the means of achieving that laudable end.

I will say a few words about Britain and the renewal of Trident, and about the goal of a world free of nuclear weapons, and that will probably be enough. On the question of Britain’s renewal of Trident, I underscore what I said in the intervention that the hon. Gentleman generously allowed me to make. The Trident missiles that currently constitute the British strategic nuclear deterrent are not up for renewal. They have decades of life left in them. The only question is whether we should replace the submarines that carry them.

Of course, one could argue that not replacing the submarines would effectively disarm this country of its nuclear deterrent. That is why the hon. Gentleman and the Campaign for Nuclear Disarmament would like the submarines not to be replaced. Equally, it is why I am determined to do everything that I can to put pressure on the Government to ensure that they fulfil their promise to replace them. However, I do not think that it is credibly arguable, by any stretch of the imagination, that replacing four submarines that are reaching the end of their design life with three or four new submarines to carry the same missiles – indeed, the new submarines will have a smaller missile compartment, so arguably they will carry fewer missiles, although I freely acknowledge that the flexibility in the number of warheads that can be put on missiles probably means that it is a distinction without a difference – comes anywhere near a breach of the provisions in article VI of the non-proliferation treaty, whatever one regards our undertakings as being.

As I said before, the only time frame is ending the arms race “at an early date”. We have never been a part of the arms race, due to our policy of minimum strategic nuclear deterrence, and as far as I can see, there is nothing in the treaty that says that we must go for a nuclear-free world before the world is conventionally disarmed. In the next and final stage of my remarks, I will argue that that would be dangerous and destabilising.

To return to the point about Trident, we continue to follow a policy with the same weapons system that we have deployed ever since HMS Vanguard first went to sea in the 1990s. Whatever other arguments might be used to say that Britain ought not to build the new fleet of successor submarines, contravening the provisions of the non-proliferation treaty is not one of them.

Let me move to the final component of my argument, which is whether a nuclear-free world would be desirable, or a least a nuclear-free world that was introduced prior to general and complete disarmament – conventional disarmament – which is referred to in the same clause of the NPT that refers to a world free of nuclear weapons.

If nuclear weapons had not existed, it is unlikely that the cold war would have remained stalemated, as it did, rather than boiling over into a third global conflict. If nuclear weapons ceased to exist, but the world remained armed to the teeth and still as mutually hostile as it is, there would be nothing to prevent the first nation to cheat on the question of its abolition of nuclear weapons from using – that is, firing – secretly manufactured devices before any such temporary monopoly of them was broken.

I particularly draw attention to the example of what happened with a treaty that undoubtedly would have had the support of the Campaign for Nuclear Disarmament in 1972, when it was signed: the biological warfare convention. I always remember that brilliant columnist, Bernard Levin, who wrote an article at the time of the biological warfare convention, talking about the fact that the Russians were apparently disposing at sea of all sorts of horrible biological weapons, under the terms of the treaty. He said that whatever things they were consigning to the depths of the ocean, he was pretty sure that biological weapons were not among them. He was dead right, because we now know that in 1973, the year after Russia signed the treaty, the Soviet leadership set up Biopreparat – a massive organisation – secretly to continue its deadly biological weapons research into such charming weapons as smallpox, bubonic plague, anthrax, brucellosis, tularaemia and Ebola.

We know about this because in 1989 – I remember when it happened – a defector from that organisation, Vladimir Pasechnik, revealed everything that was going on. We were able to get away with that cheating, because we had the ultimate fall-back of a nuclear deterrent system, which meant that it would have been just as dangerous for Russia to have exploited its secret monopoly of biological weapons, which it kept while everybody else kept to the terms of the treaty and disarmed. We would have been able to retaliate against those weapons with our nuclear deterrent, but heaven help us if we had not the nuclear deterrent as a back-up.

The question that people who advocate a nuclear-free world have to ask themselves is this: is it a sensible policy, in the real world as we know it today, to make the world safe once again for conventional warfare between the great powers? I would love to see a nuclear-free world, but I would love to see it only when I see a weapons-free world; for that to happen, there has to be a world Government and, above all, a reformation of the mind of man and a change for the better in human nature.

[ ... ]

[The Parliamentary Under-Secretary of State for Foreign and Commonwealth Affairs (Alistair Burt): … If anyone wanted to listen to as good and clear an exposition as possible of whether the United Kingdom should have nuclear weapons, they could do a lot worse than listen to the hon. Member for Islington North (Jeremy Corbyn) and my hon. Friend the Member for New Forest East (Dr Lewis). It is clear to all of us in the House, having known them for a long time, that not only do they know what they are talking about, but they continue to conduct the debate on a serious issue in exactly the sort of terms that we would want for an argument of such seriousness. As the years ebb and flow, it remains uncertain which argument will dominate at any particular stage in British politics and the like. That the reasons for and against are put so clearly is of benefit to all of us in the House, so I very much appreciate the hon. Member for Islington North calling for the debate, and the way in which he led it, as well as the way in which all other colleagues who have spoken contributed.

As always, we need to go a little way down memory lane. The first time that the hon. Member for Islington North and I debated the subject was when we were both councillors on Haringey council in 1981; he was either proposing or part of a movement to declare the borough a nuclear-free zone. Probably the first time that I came across my hon. Friend the Member for New Forest East was when he was campaigning with Tony Kerpel and others in the anti-CND movement about the same time. Both have proved their point: Haringey has, mercifully, been free of attack since the council declared it a nuclear-free zone –

Jeremy Corbyn: I made my case.

Alistair Burt: Absolutely. To that extent, the hon. Gentleman was absolutely right in how he conducted the case.

The world has of course benefited from the case put forward so ably by my hon. Friend the Member for New Forest East. It is a case with which I am broadly in agreement: our possession of nuclear weapons has contributed to the peace of the world, provided it has been allied to a commitment, demonstrated by successive Governments, to rid the world steadily of nuclear weapons through measures of mutual confidence. I appreciate the restatement of the Opposition position by the hon. Member for Bristol East ([Shadow Foreign Minister] Kerry McCarthy), who echoed the position of successive Labour Governments and reiterated the 2007 commitment, made under a Labour Government, to proceed with Trident. In general, I accept that she has restated a relatively common position … ]