Why it is that #WeAreNotAfraid

Helicopters overhead, armed C7lj5FsVUAAG9Jw.jpg_largepolice on the corners, dangerous lunatics on the loose – all of that is business as usual for the myrmidons of Westminster. After a while, you don’t notice it. Yesterday, though, you certainly did.

Yet every cloud has a silver lining. Let me offer one for the residents of London. This was a really awful terrorist attack. Not in the sense of being dreadful carnage; but in the sense of being a bit rubbish.

On the scale of terrorist attacks, it’s something like a C-, and only half a step up from a total fail. Which is a sign that, hard as it may be to believe against the backdrop of the past two days, we’re winning the war on terror.

I’m aware that it sounds incredibly insensitive to talk in this way when good people are mourning needless deaths, and when the price of keeping the bodycount low was heroic sacrifice. But if we are to be resolute, rather than terrified, we need to put these events in context.

The fact that we are a free, open, tolerant society exposes us to a risk of terrorism. It is, in principle, quite easy to find ways in which homicidal maniacs can do us harm. Our world is a bit like the glass window of a department store, thin, fragile and endlessly tempting to the maladjusted.

Except, of course, that department store windows rarely are smashed. That’s not because the glass has been made unbreakably tough; it’s because the world outside the window has been arranged such that the glass is seldom attacked.

Likewise with terrorism. The trick, if you are in counterintelligence, is not about lining every street with police snipers, or having the cast of 24 on speed-dial. Ideally, it’s about making sure the attack doesn’t happen in the first place. And, if that fails, it’s about making sure the damage is as limited as it can be.

You can ride a London bus in safety.

In 2005, London saw what happens when that goes wrong. Four terrorists, linked to an international network, acquired enough explosives to detonate four simultaneous suicide bombs in the space of an hour. That represented multiple failures on the part of the authorities – a failure to spot the bomb-making, the recruitment, the links to terrorists overseas, the planning and the attack itself.

But in 2017, the best that terrorism can do is inspire a lone loony to drive a car down a pavement and attack passers-by with a kitchen knife. This wasn’t a Paris, where men with automatic rifles launched a military-style assault; this wasn’t a Brussels, with bombs on the underground. It wasn’t one of the nightmare scenarios that SO19 spend their time training for.

That reflects years of careful, patient work by MI5, GCHQ, the police and other agencies. It’s not that Tuesday’s attacker didn’t want to cause more damage – I’m sure he did. But I suspect that, if he had tried to get his hands on a gun he’d have been picked up; if he’d tried to build a fertiliser bomb, he’d have run into the invisible watchers; and if he’d tried to get help from the people around him, someone would have turned him in.

You can’t stop a loony with a breadknife who decides, on the spur of the moment, to kill. But, touch wood, we seem to be stopping all of the others. The ones with the brains and the plans and the evil ambition to turn our world into a tool of destruction. If ISIS has reached the sorry state of having to claim this as the best they can do, then they are not half as scary as they’d like us to think.

None of this detracts from the tragedy of yesterday. But it gives me the confidence to walk across Westminster Bridge tomorrow.