Did we not hear earlier this year the horrifying tapes in which wannabe-bomber Jawad Akbar fantasised about bombing the Ministry of Sound nightclub. "No one can turn around and say, 'Oh, they were innocent'," he sneered, "those slags dancing around. Do you understand what I mean?"
The targetting of an airport was also predictable. Only last year, other young men were plotting to kill themselves and murder their fellow-passengers on flights from Heathrow to America.
So we should be well aware by now that these people are without compassion. Happy to kill themselves in the service of their pernicious political ideology, they are utterly indifferent to whom they take with them, whether they are men, women, children, Christians or Muslims. All they want to do is to destroy and kill in the name of Allah, who to most Muslims is a God of love and to them is a justification for their perverted acts of hatred.
Yet although we know all this rationally, it was nevertheless blood-freezing to see the scenes at Glasgow airport on Saturday to watch on our televisions two men so crazed with bloodlust that in front of our eyes they tried to turn a terminal packed with families into a fireball, were so happy to suffer an agonising death themselves that one of them poured petrol over himself, and had such a sick notion of their religion that one of them dishonoured their god by screaming 'Allah, Allah' as he grappled with his captors.
Even more blood-freezing is that one of the pair is alleged to be an Iraqi doctor who worked as a locum in nearby Paisley, that a Palestinian-Jordanian neurologist from the North Staffordshire Hospital is suspected of being the ringleader of the plot and that two other suspects also have a medical background.
Now we shouldn't be surprised that murderous Islamists are well-educated. Contrary to what the hand-wringing liberal Establishment still chooses to believe, there is ample evidence that it is not among the deprived that this evil madness mainly flourishes.
Osama bin Laden comes from a rich and privileged family; Mohammed Atta, leader of the Twin Towers assault, was a qualified architect; two of the 7/7 bombers studied at Leeds Metropolitan University; Jawad Akbar, who wanted to blow up British 'slags', was studying mathematics, technology and design at Brunel University.
In his fascinating memoir, The Islamist, Ed Husain describes how he was brainwashed into spurning the spirituality and tolerance of his comfortably-off Muslim parents and becoming instead a fanatical, ruthless ideologue who used colleges and universities as a recruiting ground.
But there is something shocking about the involvement of doctors. Could people trained to heal really set out to kill in the name of an ideology?
Well, yes. Don't we remember Josef Mengele, the Angel of Death at Auschwitz, who murdered for Nazism and tortured for science.
What is more worrying is that these doctors apparently come from the Middle East. The security services are already overstretched in trying to identify and deal with homegrown British terrorists: they will be deeply dismayed if Britain has become a target for foreign murderers.
Chilling though it is that young British men wish to kill their compatriots, at least MI5 and the police know what they are dealing with.
Despite the tragedy of 7/7, the security services have an impressive record in identifying, infiltrating, spying on and thwarting conspirators.
Up to now, their nightmare has been the 'cleanskins' the plotters with no form. How are they to deal with cleanskin foreigners?
Of course, we have had dangerous foreign Islamist ideologues operating in Britain for many years. The Egyptian Abu Hamza al-Masri was the evil genius of Finsbury Park Mosque.
Omar Bakri Mohammed, a Syrian, spent 20 years travelling around Britain recruiting young people like Ed Hussain to Hizbut- Tahrir, a radical group which often acts as a staging post on the way to violent jihad. (Both, incidentally, lived on benefits.)
But at least these people operated to some extent in the open and it was possible to keep tabs on them.
There now seems to be a horrendous possibility that well-qualified people of apparently respectable background are coming into this country to take up jobs that give them status, while plotting to slaughter citizens of the country that has welcomed them.
This is a terrible new vista for Gordon Brown to contemplate.
He is fortunate, however, that the political tide has turned on immigration and security.
The country has been betrayed by all those politicians who over the past decade have been insouciant about untrammelled immigration and open borders, but finally, with the electorate showing the signs of revolt, there is a general consensus among our rulers that they had better try to get a grip on numbers and some control over access.
Our new Home Secretary has so far shown herself calm, considered and sensible: we have been spared the histrionics of her predecessor, John Reid.
We have to hope that she, David Milliband, the Foreign Secretary, and, above all, the new Prime Minister, come to terms with the seriousness of the threat to the country they are governing.
Appointing Hazel Blears to encourage social cohesion and adding Britishness to the curriculum will not somehow magically remove the Islamist threat that faces us all. We require our Government to abjure political correctness, to get control of our borders and while cherishing our liberties giving the security services what people and powers they need.
As for us, the public, we should be vigilant, but we should not be afraid. Islamist ideology is as wicked and contemptible as Nazism: our values of decency and tolerance will prevail.