Those charged with keeping Britain safe from Islamist-inspired terrorism have always been clear that it was a question of when, not if, there would be another attack as I say in The Sun this morning.
The one thing that has surprised the security services about this attack is the age of the terrorist. Up to now, their focus had been on angry young people. No one was planning for a 50 something terrorist.
Our way of life should not change in response to this terrorist attack. But there are things we can do to combat this threat more intelligently.
The security services don’t have the manpower to follow everyone who appears on their radar as the Westminster attacker Khalid Masood did; it takes 12 people to keep one person under close surveillance. But we can help them by locking up some of the more obvious threats. It does seem absurd that those convicted of trying to join Islamic State can receive prison sentences of as little as two years. Anyone who is convicted of wanting to join this group should be behind bars until they are no longer a danger to the public.
The tech companies need to face up to their responsibilities too. Senior security figures are furious at the intransigence of some of these companies. I understand that one of them was reluctant to remove an online guide to which truck to rent to cause the most deaths in a vehicle attack.
The steps various tech companies have taken to deal with child sexual exploitation online shows that they can do more. And they should.
There is going to be a need far more armed police officers too. One of the security services' great worries is a terrorist trying to shoot as many people as possible in a small town. In many cases, the nearest armed response team would be over a hundred miles away.