However it is only in the early 1930s, when he is out of office and launches his campaign to warn of the dangers of a rearmed Germany under the leadership of Adolf Hitler, that we reach the real ‘meat’ of this work. Churchill becomes ever more alarmed at the turn of events in Europe, as he was by the folly of the Baldwin Government to continue down the path of disarmament while, beyond 3,000 miles of Atlantic, the United States remained resolutely aloof from the unfolding crisis.

These were Winston Churchill’s ‘Wilderness Years’, years when – despite the cogent arguments he presented to Parliament and his detailed marshalling of the facts drawing attention to the enormous scale of German rearmament – none would listen to his warnings, and the governments of Britain and France clung ostrich-like to their avowed policy of appeasement. By the time of the Munich crisis (September 1938) – when the governments of Britain and France sold down the river the liberties of the Czechoslovak peoples in a shameful attempt to buy time for themselves – Churchill could count on the fingers of one hand his true political friends and allies in Parliament.

Though 1940 and his wartime years as Prime Minister were, undoubtedly, his glory years, it is my belief that, in terms of moral courage and dogged determination, Winston Churchill’s finest hour was in the late 1930s when, reviled by his Party, and denounced as a ‘war monger’, he continued his valiant though vain battle to alert the British people to the impending danger, convinced that united and decisive joint action by the former Allies – Britain, France and the United States – could stop Hitler in his tracks and, even as late as 1936, that it could do so without a shot being fired.

After Munich - the point at which Prime Minister Neville Chamberlain proudly proclaimed that he had in his hand a piece of paper, bearing the signatures of Herr Hitler and his own, vowing that Britain and Germany would never go to war again – the scales slowly fell off his fellow countrymen’s eyes, as Hitler’s brazen determination to tear up not only the Treaties that had ended the First World War, but all Agreements he had subsequently entered into, became increasingly apparent.

Finally, the tide of public opinion began to turn against the architects of Appeasement, and a growing ground swell of public opinion came to be heard, demanding Winston Churchill’s return to high office. However it was not until 3 September 1939 – the very day the Second World War was declared and as Hitler’s tank armies invaded and occupied Poland – that Winston Churchill was called back to his old post as First Lord of the Admiralty and charged with the task of preparing the Royal Navy for war with Germany for the second time in a quarter century. In the instant of his return to the Admiralty the signal was flashed to the Fleet: ‘Winston is back.’ As he himself recounted in his War Memoirs:

So it was that I came again to the room that I had quitted in pain and sorrow almost a quarter century before . . . Once again we must fight for life and honour against all the might and fury of the valiant, disciplined and ruthless German race. Once again! So be it.

How quickly the world forgets – and the younger generation almost certainly has no idea – that it was Britain and France who declared war on Nazi Germany, for the violation and invasion of Poland, with which they were bound by a treaty of alliance.

There followed the so-called ‘phoney’ war, in which on the Western Front there was no opening of hostilities on land, though at sea the war was very real. It was not until 10 May 1940 that Hitler felt strong enough to launch his blitzkrieg against France, Belgium and Holland. On that same day, as the rising political storm in Britain swept Chamberlain from office, Winston Churchill was invited to become Prime Minister.

Far from being daunted by the task that lay ahead, Churchill was exhilarated. As he confided in his War Memoirs:

As I went to bed at 3.00 am, I was conscious of a profound sense of relief. At last I had the authority to give directions over the whole scene. I felt as if I was walking with destiny, and that all my past life had been but a preparation for this hour and for this trial.

In the absence of any effective armaments, beyond the power of the Royal Navy at sea and the fledgling, but as yet untested, Royal Air Force in the skies, Winston Churchill deployed his powers of oratory in all their simplicity, majesty and eloquence. Those who had refused to heed his blunt warnings of harsh reality in the peace-time years of the 1930s became his avid listeners and partisans once battle was joined. Churchill was shocked by the speed with which, in quick succession, the Belgian and French governments surrendered to Hitler. He was utterly determined that Great Britain would not succumb in the same way.

I recall my late mother, Ambassador Pamela Harriman, telling me about those critical days in late May and early June of 1940, as the British Army fell back on Dunkirk and retreated across the Channel, France was falling and Hitler prepared to launch Operation ‘Sealion’ – codeword for his invasion of Britain. My mother, just 20 years old and six months pregnant with me, was living with her in-laws at 10 Downing Street. They would normally dine early, frequently just my mother and my grandparents together as, by 9.30 or 10.00 p.m., the first air raid warnings would sound and my mother and I would be sent to the basement.

She related how, one evening, the Prime Minister was brooding at the dinner table, preoccupied with his thoughts. Nothing was said. Suddenly he drew his eyes into sharp focus on to my mother’s and growled fiercely: ‘If the Hun comes, I am counting on each one of you to take one with you before you go!’ ‘But Papa,’ exclaimed my mother, ‘I don’t have a gun and, even if I did, I would not know how to use it.’ ‘But, my dear,’ rejoined my grandfather, his voice increasing in power and menace, and with his fist held high: ‘You can go to the kitchen and grab a carving knife!’ Though he never used such direct language in addressing the British people, it was with that same spirit that he inspired the nation.

Now, at last, the nation was eager to listen, and willing to follow his lead, as he evoked and proclaimed their innermost instincts. Though it might be against all reason, they came to share Churchill’s conviction that, come what may, we could survive in our island, succoured by our Commonwealth and Empire across the seas and, soon, with the powerful material support of the United States under the Lend-Lease Agreement.

But Churchill was sufficient of a realist to know that, on her own, Britain did not have the strength to liberate the nations of Occupied Europe and defeat Nazi Germany. His game-plan was simple: to play for time and hold out until the ‘Great Republic across the seas’ as he fondly called America, the land of his mother’s birth, could be persuaded to join the fray. Many of his speeches were aimed at engaging not only the material support but the active involvement of the United States.

In his Address to the House of Commons (18 June 1940) in what has come to be known as the ‘Finest Hour’ speech he famously declared:

What General Weygand called the Battle of France is over, I expect that the Battle of Britain is about to begin. Upon this battle depends the survival of Christian civilisation. Upon it depends our own British life, and the long continuity of our institutions and our Empire. The whole fury and might of the enemy must very soon be turned on us. Hitler knows that he will have to break us in this island or lose the war.
If we can stand up to him, all Europe may be free and the life of the world may move forward into the broad sunlit uplands. But if we fail, then the whole world, including the United States, including all that we have known and cared for, will sink into the abyss of a new Dark Age made more sinister, and perhaps more protracted, by the lights of perverted science. Let us therefore brace ourselves to our duties and so bear ourselves that, if the British Empire and its Commonwealth last for a thousand years, men will still say ‘this was their finest hour!’

It would be difficult to exaggerate the sense of profound relief that swept over him when, some 18 months later, he heard of the Japanese attack on the US Fleet at Pearl Harbor, sure in the knowledge that America would now be engaged ‘up to the neck and to the death’.