The Great Wall of China, the walls of Rome and every medieval city, the Siegfried Line, the Maginot Line, the Atlantic Wall; nations – empires, dictatorships, democracies – have used every mountain chain and river to keep out foreign armies. And now we Europeans treat the poor and huddled masses, the truly innocent of Syria and Iraq, Afghanistan and Ethiopia, as if they are foreign invaders determined to plunder and subjugate our sovereignty, our heimat, our green and pleasant land.

Barbed wire along the Hungarian border. Barbed wire at Calais. Have we lost the one victory which we Europeans learned from the Second World War – compassion?

Since our latest cliché-rag is to tell the world that the refugee “crisis” is the greatest since that war, I was reminded of how Winston Churchill responded to the German refugee columns fleeing through the snows of eastern Europe in 1945 before the advance of the avenging Soviet Army. These, remember, were the civilians of the Third Reich – those who had brought Hitler to power, who had rejoiced at Nazi Germany’s barbaric genocides and military victories over peaceful nations. They were the people of a guilty nation slouching towards Year Zero. It was years since I read the letter Churchill wrote to his wife, Clementine, on his way to the Yalta conference in February of 1945.

But I looked it up this weekend, and here is the key section: “I am free to confess to you that my heart is saddened by the tales of the masses of German women and children flying along the roads everywhere in 40-mile long columns to the West before the advancing armies. I am clearly convinced that they deserve it; but that does not remove it from one’s gaze. The misery of the whole world appals me and I fear increasingly that new struggles may arise out of those we are successfully ending.” Churchill would have called his sentiment “magnanimity”. It was compassion.

Incredibly, it is Germany – the nation from which tens of thousands of refugees fled before the Second World War, and from whose armies they would flee in their millions after the conflict began – which is now the destination of choice for the hundreds of thousands of huddled masses trekking across Europe. Germany’s generosity flares like a beacon beside the response of PR Dave and his chums. Didn’t our Prime Minister ever read Churchill? Or did he read too much Tennyson? He likes to quote a line from Tennyson’s Ulysses – “To strive, to seek, to find, and not to yield” – which was inscribed on the athlete village wall at the 2012 London Olympic Games. But did he also, I wonder, enjoy Tennyson’s own favourite sonnet, Montenegro, in which our Victorian Poet Laureate rejoices at the Montenegrin “warriors beating back the swarm/Of Turkish Islam…”? A good word, “swarm”. “A good starter but it is a bad sticker,” as Churchill himself warned in a pre-war message to Hitler of the Fuhrer’s contempt for another benighted people.

More than 30 years ago, in Jerusalem, I met that prince of journalists, James Cameron. He had defended my reporting of Northern Ireland – and so, of course, was a hero of mine – but he, like Churchill, was a man of great compassion. I thought of him not long ago when I was complaining about another group of feral Syrian boy refugees who had been following me down a Beirut street. Almost  40 years ago Cameron was reporting for the BBC on another fleet of refugees seeking salvation on unseaworthy vessels.

“It was a dishonest journalistic compromise to call the Vietnamese refugees the ‘boat people’,” he wrote in his script, “which has an almost comfortable sound, like people on a holiday cruise. Refugees… are fugitives, escapers, victims, the lost and the lonely… Jewish refugees, Arab refugees, German refugees, Indian refugees, Pakistani refugees, Russian refugees, Bangladeshi refugees, Korean refugees.” Cameron recalled the 17th-century Huguenots who fled to Britain, the persecuted Jews who fled from eastern Europe to America in the 1900s.

And then Cameron came close to a “PR Dave” moment. “In those days the world was a pretty empty place; there was room almost everywhere for the homeless stranger. Everywhere to which an alien might wish to take refuge is now overpopulated, and already with problems of its own.” And some refugees “are avaricious, some are saving their skin, some are on a bandwagon. But I have yet to meet a refugee baby who left home other than because he had to”.  There was no “divine ordinance”, Cameron asserted, “that says you must stay where you were born.”

Were the followers of Moses not refugees, as they continued to be for 2,000 years, “until they replaced their exodus with someone else’s?”

A unique irony of our modern-day tragedy is that an Irish naval vessel has been saving the lives of thousands of shipwrecked refugees a few miles from the Libyan coast. A century and a half ago the Irish famine exodus was washing its refugees up on the coast of Canada, the vessels filled with men, women and children dying or dead of typhus, received with compassion – but also with fear that their plague would contaminate the people of the Canadian Maritimes.

It fell to Pól Ó Muirí, the Irish-language editor of The Irish Times, whose own father was a migrant construction worker in Britain, to point out last week how many Irishmen helped build the Channel Tunnel – and of how today “the migrants are on the other side, trying to get through”.

Yes, “something should be done” about the refugees, Ó Muirí rhetorically agreed. But then – and since I love great writing, you must bear with me – he added: “The whole thing is a bit frightening, isn’t it, all those people throwing themselves at the fences at the mouth of the tunnel that the Donegal ones helped build… It was when the camera panned back to show men standing and watching, with all the dignity they could muster, that I suddenly realised I was seeing… my father in England… Do you see your family in their faces too? Look a little closer. Don’t be afraid.”

As they say, necessity knows no law. Nor does compassion.