Sir Julian Lewis: One of the advantages of being called at a late stage of the debate is that I can put my hand on my heart and truthfully say that every single speech in this debate so far has been outstandingly good. I have agreed with virtually every word of every one of them, and looking at the calibre of the remaining people, including all three Front-Bench representatives, I have every confidence that the standard will be maintained till the end.

A former occupant of your chair, Madam Deputy Speaker, used to give courses in good public speaking technique. He always said, “If you wish your speech to have any useful impact after the event, it should not contain more than one, or at most two – and that is stretching it – key points.” So here is my one key point, which, I am delighted to say, has been touched on very effectively by the hon. Member for Llanelli (Dame Nia Griffith), among others: any settlement that does not have a military presence on the ground of unoccupied Ukraine from the country or countries offering a security guarantee will be a disaster. I ask the House to consider Europe at the end of the second world war, when the tripartite alliance had largely broken down, and Stalin was in occupation of eastern Europe and, of course, the eastern half of Germany, which his troops had conquered. The west was in occupation of the remainder of the European continent – literally, in the case of West Germany.

What would have happened – knowing what we know now about the nature of Soviet communism – if, instead of the victorious western allies maintaining a very large military presence in occupied western Germany, they had said, “Right, we’ll demilitarise this and clear out, but we’re going to give the West German politicians who follow a security guarantee that if any trouble happens, we will stand by them”? The only thing that stopped a conflict breaking out between the Soviet occupying forces and the western world was the fact that, right up against the dividing line between Soviet-dominated East Germany and the rest of Germany, there were western allied troops, and it would have been impossible for the Soviet forces to move against West Germany without immediately triggering a major military counter-action.

I have often said – and I make no apology for saying it again – that it is worth looking at the two halves of the 20th century. In the first half, we had two global conflicts – two world wars. In the second half, despite the intense ideological and military rivalry between the communist world and the democratic western world, we had no global conflicts – no third world war. I put that down to two factors. One was unprecedented: the nuclear balance of terror. But it was not enough to stop all forms of conflict, because it is possible for conventional conflicts to go ahead under the threshold of the nuclear balance without necessarily triggering Armageddon. That is why we have to have strong conventional deterrent forces, too.

So, what was the other factor preventing the cold war from becoming the third world war? It is quite clear that it was the most successful alliance in history: the North Atlantic Treaty Organisation. It grieves me to say that because of some of the occupants of high office in the capital of our ally the United States, the future of the NATO alliance – and therefore the future of world peace, frankly – is hanging by a thread.

It was the chief staff officer and representative on the war time chiefs of staff committee of Winston Churchill, General Sir Hastings Ismay, who became the first Secretary-General of NATO. He is credited with having made the rather pithy but nevertheless very accurate observation that the purpose of the alliance at the time it was founded was threefold: to keep the Americans in, to keep the Russians out, and to keep the Germans down. That third element fortunately became redundant as West Germany developed into a democracy – so quickly, in fact, that in May 1955, 10 years virtually to the day from the surrender on Lüneburg heath of the Nazis to General Montgomery, Germany itself was admitted to the NATO alliance.

I ask people to take another counterfactual look at history. If the Kaiser had known in 1914 that if he invaded neutral Belgium, he would immediately be at war with the United States of America, would he have done it? I think the answer is no. If Hitler had known in 1939 that if he invaded Poland, he would immediately be at war with the United States of America, would he have done it? I think the answer very probably is no to that as well. Therefore, the secret to keeping the peace in the world is to keep America engaged with the security of Europe.

America is going through a phase at the moment – which seems to hinge on a number of personalities who hold power in that great democracy, apparently with the approval of a majority of the electorate – in which its commitment to European and thus world security is in doubt. This is the chance for Europeans, whether inside the EU or, like us, outside it, to show that we can do our bit. We have to keep the show on the road until America once again stands up for the policy of the second half of the 20th century, which stopped the third world war, rather than it reverting to its policy of isolationism from the first half of the 20th century, and standing by, which caused two global conflicts that could have been prevented.