Every year on 12 July, I think of that Frenchman and wonder: why are political sympathies towards Ulster the wrong way round? Why does the right support the Unionists, and the left the Nationalists?
To the extent that the Unionists now have any friends at all in England they are found on the Tory right and in the Fogey Press, a friendship that hasn't done the Ulstermen much good. And to the extent that Irish republicanism has supporters here, they are on the left of the Labour party.
The Guardian doesn't support Sinn Fein and the IRA (though one or two of its columnists do), but it has some sympathy for the broader nationalist position. The Daily Telegraph vehemently supports the Unionists.
If anything, the left's position is more dishonest, the right's more puzzling. In the 19th century, Liberals came to see Ireland as another "nation struggling justly to be free", and extreme Irish nationalists of the Fenian school excited radicals everywhere when they attacked landowners.
During the long dispute over Home Rule, from the 1880s to the 1920s, this Fenian idea hovered in the background. It was generally apprehended - hoped by some and feared by others - that an autonomous Ireland would represent a grave threat to property and the established social and economic order, which just goes to show how wrong you can be.
During that period, British governments, Tory more than Liberal, tried to kill Home Rule with kindness, governing Ireland gently and buying out the large landowners. This did not, in the event, keep Ireland in the United Kingdom. Instead, it turned the Irish from a race of starvelings and outlaws into a nation of sturdy small farmers and traders, and in the process made Ireland the most politically and socially conservative nation in Europe.
But the left have never quite come to terms with that. My colleague, Alan Watkins, once wondered in print why his fellow socialists were so keen to force a million Ulster people, of Protestant religion and none, to live in what he called, with his own touch of Celtic hyperbole, "the most reactionary theocracy west of Tehran".
Not long ago, that wasn't really such an exaggeration. Until the 1970s the sale of artificial contraceptive devices was illegal in Ireland, as consensual adult homosexuality was until the 1990s. Divorce became possible, in strictly limited conditions, only a few years ago, and abortion remains totally prohibited by the constitution until this day.
An even more startling case was unknown until Nuala O'Faolain of the Irish Times unearthed it not long ago. A man can only use his imagination, but few innovations of the past half-century can have done so much for human happiness in a simple way as the sanitary tampon.
In the countries where it was introduced, that is: these did not include Ireland. When the tampon arrived in the 1950s, it came to the attention of the Catholic Archbishop of Dublin, who was alarmed that its use might be dangerous for excitable young girls, and expressed his concerns to the minister of health. Since this was independent Ireland, the health minster did as he was told, and the tampon was kept out of the country for years after. And how people still laugh at those Orangemen who said that "Home Rule will mean Rome rule"!
A tendency to overlook reality has always been a characteristic of the left, and maybe a morally necessary one. If you pay too much attention to the fact that most schemes of human improvement do tend to go wrong, then you might as well give up and never attempt any more improvements.
But a higher degree than usual of self-deception has been needed in the case of Ireland. As Irish historian Roy Foster nicely puts it, "the psychological reasons for this determined evasion are easy to find: it is difficult, if not morally impossible, for the left to admit that an independent Irish state has become so decisively different from the left's vision of what it should be".
And yet, as against the left's myopia, the right's attitude to Ireland is almost more perverse. The two Telegraph newspapers, Daily and Sunday, greatly dislike abortion. Shouldn't they therefore warm towards a state which forbids it? Shouldn't they admire this rare country which has tried to impose Christian morality by force of law?
Should they not feel sympathy for "the Ireland we have dreamed of"? That Ireland was described on St Patrick's Day 1943 by Eamon de Valera, the Irish prime minister. It would be "the home of a people who valued material wealth only as the basis of right living, of a people who were satisfied with frugal comfort ...
"A land whose countryside would be bright with homesteads, whose fields and villages would be joyous with the sounds of industry, with the romping of children, the contests of athletic youths and the laughter of comely maidens." It could have been said by Marshal Petain at just the same time. It was the quintessence of right-wing hearth-and-home rhetoric. And it was the vision of the greatest Irish republican of the century.
More than 50 years later, Dr Noel Browne looked back at "de Valera's blueprint for the proudly `Catholic state for a Catholic people' ". Browne had his own axe to grind. In the short-lived coalition government of 1948- 51, after de Valera had been in power for an uninterrupted 16 years, Browne was a short-lived minister of health.
He wanted to introduce a modest measure of maternity welfare, but this was vetoed by the dominant force in independent Ireland, the Catholic hierarchy. Browne was forced to resign (and appalled his colleagues by telling people why ), never to hold office again.
Not long before his recent death in great old age, Browne wrote to the Irish Times, as an old republican but also an old leftist, provocatively contrasting the two parts of Ireland. "With all its warts, the North represents the Europe of the Reformation, the Enlightenment, the Renaissance, the French Revolution, the Industrial Revolution, and much else."
This was written to annoy, but didn't Browne have a point? What the Orangemen are celebrating on the 12th, after all, is the Battle of the Boyne. William of Orange's victory over James II may have had tragic consequences for Catholic Ireland. But it also meant that for the next century, enlightened Europe looked longingly towards England, as the country which had overcome monarchical absolutism and clerical reaction.
Maybe there should be two festivals in Ireland and beyond. On St Patrick's Day, not only Irish nationalists but all romantic reactionaries would dream of theocratic governance, athletic youths, comely maidens.
And on 12 July, not only Protestant Unionists but liberal and anti-clerical people of all lands should join with the Ulster pipe bands in celebrating "civil and religious liberty", King Billy's great victory for progress and enlightenment over the forces of darkness.