The latest terrorist plot in Britain was hatched not in the meeting places of disaffected, British-born Muslim youths leading lives of grim desperation but in the comfortable homes and offices of a well-educated group of professionals who are among the world’s most highly sought-after immigrants. It is a telling reminder that terrorism has many faces, that it can be imported or homegrown and that it is even more likely to be embraced by the educated and the comfortable than by the uneducated and the poor.

Seven of the eight people arrested by British police after two failed car bombings in London and a mercifully bungled attack at Glasgow Airport are doctors and the other is a lab technician who is married to one of them. They hail largely from the Middle East, and their profession has given them the ability to move and work freely in the West. In fact, their medical skills are in such demand that until Britain tightened its rules last year, they could set up practice without a work permit if they had the requisite credentials.

This is a huge advantage to al-Qaeda and other terrorist groups because it makes it much easier to infiltrate affluent societies and to strike at their more vulnerable points. No wonder they have sought out such people to carry out their murderous schemes.

That those dedicated to curing people’s ills could be so determined to inflict death and misery on innocent civilians comes as a shock. That is particularly so in Britain where previous Islamic terrorist events, including the horrific London subway bombings two years ago, were traced to young homegrown Muslim radicals alienated from mainstream society and hence vulnerable to the allure of extremist ideologies. The immigrant professionals keep a lower profile, but they share the same extremist ideals, the same conviction that terrorism is a legitimate response to perceived oppression and the same burning desire to do something important for their cause.

One study of 400 Islamic terrorists by a U.S. expert on extremist psychology found that 75 per cent were from an upper- or middle-class background and were either professionals or associated with them. Nine out of 10 came from only moderately religious homes and a nurturing family environment. Those who successfully make their way to the West for study and work are among the highest achievers in their own societies.

The challenge for authorities is to identify and intercept these extremists before they can do serious damage. Slamming the door on qualified doctors, engineers and other professionals simply because they hail from Islamic countries would be wrong. But a more careful vetting of applicants seeking to train or work in the West is definitely in order. The fact that the bomb attacks in London and Glasgow were botched by a bunch of amateurs should not make anyone sleep easier. There will be other fanatics who will try again. And before they strike they could very well be leading quiet lives as respected members of the community.