Eric Hobsbawm, according to the Spectator magazine, is “our greatest living historian — not only Britain’s but the world’s.”

You might suppose that a lifelong member of the Communist Party whose voluminous works enjoy such accolades even from conservative journals, who has been made a Companion of Honor by the bourgeois British state he has done so much to undermine, and who has just reached the grand old age of 90, would now exercise a little reciprocal generosity toward the younger generation.

It seems, however, that Professor Hobsbawm is — as Winston Churchill’s father, Randolph, said of Prime Minister Gladstone — “an old man in a hurry.”

At a London garden party last weekend, Mr. Hobsbawm came to a stall serving crêpes to find two small children standing in line ahead of him. The food was taking a while to cook and so, unaware that he was observed, the great man deftly moved in front of his equally hungry but less impatient juvenile competitors. The children went very quiet and blushed, as good children do when they see a grown-up behaving badly. Another adult, however, politely pointed out to the professor that there was a line. Without an apology, Mr. Hobsbawm retreated. As soon as he thought the coast was clear, he jumped the queue again.

All his life, Mr. Hobsbawm has insinuated, more or less subtly, that socialism is more civilized and humane than capitalism. Good Marxists, though, believe that bourgeois morality is for the bourgeoisie, not for them. There is nothing indecent about taking candy from a baby, because decency is mere ideology.

Mr. Hobsbawm’s little faux pas tells us more about what has gone wrong with Britain than any of his tendentious history books. Decency, that indefinable but instantly recognizable trait that used to define the English character, has not disappeared, but it is no longer given public recognition. The image of the gerontocrat pushing aside posterity neatly sums up the demographic disaster that is Europe.

This week the former Conservative Party leader, Iain Duncan Smith, published a 671-page report about the breakdown of the family and its catastrophic consequences, the cost of which he estimates at $200 billion a year. He concluded that the status of marriage, the monogamous, heterosexual, old-fashioned kind, must be restored if Britain is to have any future at all. He wants taboo words like “husband” and “wife” to reappear on official forms, the tax and welfare system to stop discouraging parents from living together, and the government to reward hard work and independence instead.

Needless to say, Left-wing commentators denounced Mr. Duncan Smith’s package of reforms before they even had read it. The present Tory leader, David Cameron, gave a cautious welcome to the proposals by Mr. Duncan Smith, who has single-handedly reconquered the “social justice agenda” for the Right. But Mr. Cameron stopped short of promising to reform the tax system — even though Britain is the only country that offers a huge fiscal disincentive to marry. A married couple must work more than 100 hours a week longer than a single parent to get the same welfare and tax benefits. One consequence of Britain’s dysfunctional welfare state has been the creation of an underclass of subsidized criminals and terrorists — luridly illuminated by the trial that ended this week of the four suicide bombers who tried to blow themselves up on subway trains and buses on July 21, 2005.

All four convicted terrorists had come from war-torn East Africa as children, with every opportunity to gain education and prosperity. Compared to their less fortunate contemporaries in Africa, they had won the lottery of life. Yet all four had decided to kill as many as possible of the nation that had given them a home.

Their “emir,” or leader, Muktar Ibrahim, had come from Eritrea at age 13. After leaving school he mugged old ladies for a few years. He became an Islamist in prison because, as one gang member said, “he hated this country to bits.”

On his release in 1998, he followed the charismatic hook-handed preacher, Abu Hamza, who promised him and his cronies the usual incentive of 72 virgins in paradise. This worked for Ibrahim, who already had assaulted a 15-year-old girl. One of his thugs said: “He liked white girls but he was into mistreating them and calling them bitches.” Sexual violence looms large in the fantasies of Islamists.

The counter-terrorism police knew about Ibrahim, who was trained in Sudan and Pakistan. They observed him and his jihadists training in northwest England. They even followed him to Heathrow. By now a British citizen, he was actually bound for an Al Qaeda training camp in Pakistan, but claimed to be attending a wedding there. He could not name the bride, was on bail for beating up bystanders while handing out extremist literature, had a jihadi manual and other suspicious items in his possession — but still was not arrested. Ibrahim returned to carry out his mission, which failed only because he was too ignorant of basic math to calculate the strength of ingredients to make a reliable bomb.

Morality is a continuum. The moral sense that makes decent people stand in line is the same moral sense that is so outraged by amoral terrorists like Muktar Ibrahim.

Champagne socialists who set a bad example prepare the ground for the preachers of hate. And Britain won’t win its war on terror until it rediscovers decency.