Headlam lost his parliamentary seat, Barnard Castle in County Durham, in the general election of November 1935. On the day after the result was declared his wife, Beatrice, departed for South Africa; she had been unwell for some time, and it was hoped that the sea voyage and the warmer climate would restore her health.

In September 1937 Headlam was amongst a group of foreign observers at the Nazi Party's annual rally at Nuremberg.

Tuesday 7 September 1937 This morning we all attended the first meeting of the Party Conference in an enormous building – a temporary structure – designed to hold, so they told us, about 15,000 people – it was literally packed today. We had excellent seats near the front just below the platform … The proceedings began with music (perhaps the best part of the show: a superb band) – then at last the Nazi swells began to arrive – then came a procession headed by an apparently endless supply of flags – then came Hitler followed by all the other leaders – Goering, Goebbels, Hess, Rosenberg, etc. – great enthusiasm prevailed. They seated themselves on the platform and one had a fine view of them – one was rather terrified at their appearance – they looked capabales de tout and no doubt are. Hitler himself is a bigger man than I thought – by which I mean he is of average size: otherwise, he is exactly like his pictures. A boring beginning was the reading out of the names of all the martyrs of the movement – not so many after all – then came a speech from Hess – another from Sleicher (don't know the man's name: he is the anti-Jew propagandist): then the reading of the Fuhrer proclamation … a reference to the colonial question much applauded.

Friday 11 November 1938 Armistice Day — and what a world today after those strenuous years of war. How little one thought that all that expenditure of blood and treasure would have so little result — that 20 years after we shall be, to all appearances, on the brink of another war. How helpless and hopeless we have all been since 1918 — in my heart of hearts during the war I always felt that we should learn nothing from our experiences — that as soon as peace came the cranks and fools would again obtain control — and they did — they shrieked for disarmament and pinned their faith in the League of Nations. They shut their eyes to the inevitable — and now here we are again vis à vis with Germany as we were in 1914 — only today our position is infinitely more dangerous as a result of air warfare — God knows what may be in store for us — pray that yet again he will see that England is preserved despite her follies and her thoughtlessness.

Friday 1 September 1939 Hitler began his war against Poland last night or early this morning – so presumably it is only a matter of days or hours before we are at war. It is a ghastly prospect – more especially I think to people who passed through the last war, because they can appreciate more vividly what is in store for all of us than can the present generation – and to many of them, who like myself are too old to hope for any war employment, the outlook is gloomy in the extreme – nothing for them to do but sit and wait and hope that those whom they love may be spared. Last time God knows it was all horrible enough when war came – but then at any rate one knew what one had to do – and there it was – this time one is out of everything. Well – it is no use repining: one has only got to grit one's teeth and pray that a successful end may come sooner in this war. That we shall finish Hitler in a few months seems to me ridiculous to believe. He has a magnificent fighting machine and he is absolutely ready for war. He will, I fear, eat up the Poles very quickly and then – if he can't get us to make peace – will go all out to pulverize us into surrender. His people will stick to him for a time – so long as he is successful – this in my opinion is certain.

Friday 10 May 1940 Neville Chamberlain announced his resignation on the wireless tonight: a dignified effort — Winston is to rule in his stead — so at last that man has gained his ambition: I never thought he would — well — let us hope that he makes good. I have never believed in him: I only hope that my judgement of the man will be proved wrong. He certainly possesses courage, imagination and drive[,] and age and experience and responsibility may give him judgement — then all should be well. One is sorry for Neville but I should imagine that he has only himself (and David Margesson) to blame for his fall: he should long ago have cut the dead wood out of his administration. The Germans invaded Holland and Belgium early this morning — troops dropped from the air appeared to be very busy in both countries. … No doubt we were ready for this coup. The war has now really begun and we are in for a period of strain and tension.

Monday 28 October 1940 The news today is that the Italians issued an ultimatum to the Greeks last night or in the early hours of this morning demanding the surrender of certain unspecified parts and that the Greeks refused to discuss the proposal. There is now war between Italy and Greece. I am agreeably surprised that the Greeks have had the guts to stand up to Musso: I shall be still more agreeably surprised if they can stop his armies from overrunning Greece.

Sunday 22 June 1941 The Germans began an invasion of Russia early this morning – I confess that this move has surprised me: I always imagined that Stalin would give way to Hitler and give him all he wanted – but perhaps the military people in Russia have prevented his doing this or perhaps Hitler asked even more than Stalin could stomach. I don't suppose that the ‘conquest’ of Russia will take very long – and what then – presumably either Hitler will make some kind of peace offer to us based upon our acceptance of the ‘New Order’, or he will try his hand at an invasion here or push on in the [Middle] Eastern theatre. Winston spoke on the wireless tonight and was very fierce and determined – never should we make peace with Hitler, etc., we were in this struggle to the bitter end however long it might last. This is the right attitude to adopt for the time being at any rate – meanwhile it remains to be seen what the Yanks are going to do – without them it is difficult to see how we are going to beat Hitler in this war. However, one feels that God is on our side – that's the great thing.

Sunday 7 December 1941 We heard on the wireless tonight that the Japanese have made a violent attack on the American naval base at Pearl Harbour in Hawaii and other places in the Hawaiian group of islands – American ships sunk, aircraft destroyed, heavy casualties – they are also invading Thailand and the Malay Peninsula – and all the time their Ambassador and special agent are in Washington carrying out negotiations with Roosevelt – I suppose the little swine have been preparing this coup for some considerable time – and, after all, they are only doing what they did when they fought Russia – rushing into Port Arthur and torpedoing the Russian ships before they declared war – and now they have more excuse for their methods for Hitler has used them all along in this war.

Thursday 28 May 1942 The Labour Party has been airing its views at its conference in London during the last two days — it stands for the usual things and its speakers bawl out the usual platitudes. In the old days one did not bother much about what was said at Labour conferences, but nowadays one realises that all this claptrap has a bigger and bigger following of people — unthinking people, I think. The left wing intelligentsia always strike me as the most unthinking of men: their theories are all based on the old worn out, futile, untrue assumption of equality — all men may be equal in the eyes of God, but He never made all men equal to the tasks which they are set. To institute a new order of society on the basis of equality is doomed to failure — because it implies bringing men down to the level of the least fit among them to cope with the problems of life. In such a society progress in the true sense of the word would, I am certain, be impossible — unless, indeed, it were possible to change all the human instincts. Is it likely that a man would give of his best if he were to gain no reward for his efforts? Would not the natural instinct of each one of us be to sit back and do as little as possible, if he knew that he would be kept by the State?

Friday 29 May I went to a Boys Club near Byker Bridge and afterwards went on the Byker and Heaton Conservative Working Men's Club. Everyone there was very civil to me and I drank a lot of beer — I also spoke for about five minutes which I gathered was as much as they wanted. Several men came and talked to me, asking questions — clearly the Russian complex has taken possession of some of them — it is odd how quickly propaganda has an effect upon the crowd - one might think that Russia was of more importance to us than our own country.

Tuesday 3 November 1942 … this war is becoming more and more tremendous and one can see no end to it – one doubts, indeed, whether one will live to see the end of it —I should like to and yet I dread all that is to come after it — I foresee so much disappointment and discontent as the result of all the nonsense that is being given tongue to nowadays. Why should human nature be changed for the better as a result of war? Why should we expect a better world because everyone will be poorer and yet expect to live more easily and do less work? To me the future looks very bleak and I fancy that there will be a rude awakening to realities particularly in this country where, despite all that is now said to the contrary, the bulk of the population was well off and prosperous before the war.

Friday 14 May 1943 The great news of the north African victory is becoming clearer and clearer – though whether the effect on German morale is as great as the papers would have us imagine remains to be seen … so long as they are assured that the German defences are so strong in Europe that we cannot surmount them, they will carry on despite the air bombing, etc., etc. – at least such is my conviction. We simply have got to go through with it – or make up our minds to that effect – we have got to beat the German army in Germany – and it is going to be a terrific job.

Headlam spent the first six weeks of 1944 recuperating at Holywell; he kept the diary regularly, but his knowledge of events was restricted to that provided by the press and radio. Towards the end of January he began to return to his normal routine and attended some meetings in Newcastle. However, his first visit to London in mid-February brought on further illness and he was confined to bed for the following three weeks. After this Headlam's strength recovered sufficiently for him to engage in local affairs, but he did not make another visit to the House of Commons until 21 April and only resumed a regular pattern of attendance at the end of May.

Friday 22 September 1944 The Govt.'s demobilization plans have been published and seem to be devised as fairly as possible, but there are certain to be plenty of hard cases which will cause the likes of me a lot of trouble later on! Men, who are retained in the forces after the war in Europe, are to be given higher pay which is right and proper — it is estimated that this increase will cost £100 million a year — a lot of money and where it is to come from goodness only knows, and yet I gather that some of [the] press consider that it is a niggardly business. All sense of proportion about the spending of money is gone nowadays — millions mean nothing — ‘nothing is too good for our bairns’, as the Labour people used to say in the Durham C[ounty] C[ouncil]. The idea that we can afford anything and everything after peace is restored is based on the assertion that, if we can spend so much in the war, we can spend just as much in peace. No one seems to realize that because we have to spend so much in war, we must have less to spend when it is over.