And will it end there? Of course not. Mr George Tenet, boss of the CIA, held a "summit" meeting last week with Ms Eliza Manningham-Buller, director of MI5. Her new concrete Commons - democracy with a Maginot Line - is only the beginning. Other "landmark buildings" around Britain - other "picture postcard sites" - are earmarked for the same treatment. That's £200m of extra spending, set in stone and barbed wire.
Meanwhile, police on the streets now have "shoot-to- kill" terrorist orders (according to the Times). And Manningham-Buller's finest are apparently hunting a couple of indigenous suicide bombers, who may be planning something (according to the Sunday Times) - though nobody has heard of them for a couple of years and "it is possible that they are no longer al-Qaida followers".
Stand by, next month, for the civil contingencies bill which - more scary leaks to the men of Murdoch portend - will give policemen powers to seize control of telephone companies, postal services and "even the BBC" if terrorists strike. Sir David Omand, the nearest thing Britain has to a director of homeland security, believes: "We have to move from the old idea of a secret state to the idea of the protective state. We have to be able to deal with low-probability, high-impact events."
Sorry ... what was that? A "senior Whitehall source" chimes in behind. "While there is no imminent threat we know of, the belief is that it is only a matter of time before something happens here." Welcome to the marriage of Mr Unspecified- Threat and Miss Low-Probability (not to mention their baby, little Not Imminent).
Time to take a long, deep breath. Nobody, after 9/11, would say there's not a problem. Nobody, after Riyadh, Casablanca and Mombasa, would say that it is going away. We have our cruise missiles and B52s. They have their suicide kits. There is some danger, of course there is (though probably more, on current form, if you're a Moroccan nightclub bouncer or Kenyan hotel gardener than if you're walking down Whitehall looking for postcards). But perspective, like intelligence, seems to have gone missing.