The most fundamental failing of all, however, is the Government's counter-terrorist strategy itself. Known as Project Contest, this refuses to acknowledge that the true driver of Islamist terror is religious fanaticism.
Instead, it attributes its causes to Muslim poverty, discrimination and grievances over foreign policy. In other words, it blames us.
The analysis is demonstrably absurd. Many of these terrorists are prosperous, middle class and well-educated. Indeed, two of the suspects who have been arrested are doctors. Muslims are being murdered in vast numbers in Iraq not by us, but by other Muslims.
And as Mr Brown said yesterday, the first attempt to blow up the Twin Towers occurred as long ago as 1993; Islamist terrorism is taking place all over the world and in countries where there is no connection with Iraq or the Middle East at all.
The fact is that the Islamists have always used any and every grievance - Bosnia, Kashmir, Saudi Arabia, Afghanistan, Palestine, Salman Rushdie (twice) - to recruit to their cause.
But the real source of this terror, as former extremists have told us, is the aim to conquer the West and Islamise the world.
Hat tip: Joshuapundit.