IT was just after 2.40pm last Wednesday afternoon when the division bells rang at Westminster.

The bells summon MPs to vote and wherever they are on what’s known as the Parliamentary estate they have exactly eight minutes to pass through the lobbies beside the House of Commons chamber before the lobby doors are locked and the count takes place.

Like hundreds of MPs that afternoon, when the bell sounded I set off on a journey I’ve made many, many times before, using the underground passage which connects the buildings where most MPs have their offices on the north side of Westminster Bridge Road to the Palace of Westminster and the Commons.

As we walked through, none of us were aware that just a few feet above our heads Khalid Masood had just brought his murderous drive across Westminster Bridge to a shuddering halt by ramming the railings which surround the Palace and then, on foot and armed with two knives, entered Parliament just in front of what’s commonly known as Big Ben.

As we emerged from the underground passage and walked through the colonnade to the House we became aware of a commotion just 30 or so yards away to our right in the open courtyard known as New Palace Yard – the main entrance to Parliament. We saw Masood, we saw policemen, we heard the three shots and then the police telling us to run.

We didn’t hang about, running into the House, unsure of exactly what had happened, and passed through the lobbies to vote as if on autopilot. The lock down began and soon enough black armour clad, specialist armed police completed a sweep of the estate to ensure it was safe.

It was all very surreal and then we were shepherded across the corner of Parliament Square to Westminster Abbey, together with many other MPs, peers, tourists and Westminster staff. I have never known Parliament Square to be so eerily quiet – it had been completely evacuated save for emergency vehicles and a line of armed police escorting us.

Although there are worse places to be detained than Westminster Abbey, the cold did begin to creep in! Luckily, I was with my colleague Kevin Hollinrake MP for Thirsk and Malton and thanks to my iPad we were able to Skype our families to see them and let them know we were safe.

Obviously our immediate thoughts are with the families of those who lost their lives in the attack. But reflecting further on that terrible day and with the benefit of hindsight I think we can draw a number of conclusions.

Firstly, we should acknowledge that up and until last Wednesday, we have been lucky not have suffered a terrorist attack on Parliament. More generally, relative to other countries we have not suffered a major terrorist incident for some time. For this, we must acknowledge the great record of our security services in preventing attacks before they are even launched.

Secondly, the tradition has always been to have Parliament be as open and accessible to the people it serves. Our Parliament is widely considered one of the most open in the world as anybody who has visited can testify too. But this also makes it vulnerable. The inevitable security review will have to look at this balance between accessibility and security and whether it is appropriate.

Lastly, we need to recognise to the scale of the Islamist terrorist threat which is homegrown, not imported from overseas. The attacker was born and brought up in Britain. It seems likely he was radicalised here rather than abroad. The fact that there are apparently thousands of people that potentially fit this profile is deeply worrying to me and it is no wonder the security services cannot track all of them. There is potential for radicalisation in communities, jails, schools and mosques – the government is already focussed on this issue but it must remain vigilant as should local communities. There can be no excuse for people not integrating into our way of life and then putting themselves on the conveyor belt to violent extremism.