Yesterday's attack was an attack on London, this incredible melting pot I've had the privilege to live in all my life. Home to millions of people drawn here not just from all parts of our United Kingdom but from every corner of the world and visited daily by many more. Sadly some of those visitors were among the victims of yesterday's terror.
It was also an attack on your Parliament. Make no mistake: it is your Parliament. One of my favourite parts of the job is showing constituents around the building. Although sadly it behaves like a private members club at times, it is the place where the people you choose to represent you come together to decide how we should go forward as a country. For all its faults, it is at the centre of our national life and that is why it was targeted yesterday.
And it was an attack on our society. We are far, far more likely to be killed by a lightning strike than a terrorist attack, but the fatal lightning strikes that take place across the world throughout the year aren't reported in the news. The power of terrorism is in its ability to literally terrify us - to make us change our way of life and fear our fellow citizens, dividing our societies. We must deny it that power.
So this morning I am back in the Houses of Parliament doing my job as normal. And when we find out who was responsible, who their accomplices were if any and who radicalised them, I will hold them responsible - not people who look like them. My heart goes out to the loved ones of those who lost their lives yesterday. We honour their memory best by not letting the terrorists win, by not giving in to fear or hate.
If yesterday's attack was humanity at its worst, the response to it revealed our best side. The police officers who directed others away from danger, while moving towards it themselves. The ambulance crews and staff at nearby hospitals who fought to save lives and comfort the injured and traumatised. My colleague Tobias Elwood, who did his best to save a dying police officer. Such people epitomise public service. I said after last year's tram crash that we don't say thank you enough. So to all those who helped to keep my staff and I safe: thank you.
I spent nearly five hours yesterday locked in the chamber and voting lobbies of the House of Commons with about 350 other MPs. We watched the news on TV, shared mobile phone chargers so that we could reassure loved ones we were ok and talked about the work we do. It was a reminder that although we spend most of our time arguing about Brexit, austerity, the future of our Union and so many other things, those arguments obscure the fact that there is more that unites us than divides us. We are all committed to democracy, to the idea that the way we resolve our differences is through debate, sometime passionate argument, but never violence. If politics sometimes frustrates you (it certainly frustrates me at times), that is something worth holding onto, indeed something worth giving your life to defend - as PC Keith Palmer did so heroically yesterday.
Gavin Barwell is the Conservative MP for Croydon Central
This blog first appeared on Gavin's blog, and can be read here