The March 22 terror attack on Westminster exposed the people of London to the horror that citizens of Paris, Nice and Berlin already know-that there is hardly any defense to Islamic extremist who are committed to killing.
This is the stark reality, as Londoners of all walks of life gather in Trafalgar Square, quietly, respectfully and flanked by security agencies with helicopters constantly rumbling above, to remember the people who lost their lives in the Wednesday terrors attack.
Terrorist are continually ditching the Kalashnikov and bomb for low tech car and knife.
In 2015, well armed terror cells closely controlled from inside Syria were able to bring carnage to the streets of Paris and Brussels in carefully planned attacks.
The counter-terrorism response across Europe was slow but effective, making it difficult for terror cells to organize themselves within the Muslim communities where they had sought shelter.
But this has isolated many young Muslims who have removed themselves from mainstream society so that they have become easy prey to online radicalizers.
Security services across Europe have discovered very quickly that there is little they can do to stop a lone wolf terrorist who keeps his deadly plans to himself.
In July last year dozens of people were killed when a lorry ploughed into a large crowd watching a fireworks display to mark the Bastille Day holiday.
Months later a lone attacker drove a lorry into a crowded Christmas market in central Berlin, killing several people and injuring dozens more.
Both Islamic State and al Qaida have previously urged followers to use vehicles to carry out attacks.
Police believe the man who carried out the attack on Westminster killing three people including a police officer, acted alone.
Theresa May went further and told Parliament today the suspect was British born and has previously been investigated by MI5.
Now politicians, advised by counter-terrorism experts, will turn their attention to how to combat home-grown terrorists who answer the call to jihad by using their cars and kitchen knives to carry out atrocities.