The first I knew about the terrorist bombs was a growing wail of sirens outside Parliament, and a rising sense that something was very, very wrong. Suddenly there were huddles of MPs and researchers clustered around TV monitors to hear the news. All the phone lines and mobiles crashed as everyone tried to tell their families they were safe. The number of guards with guns magically doubled, and we were told not to leave or travel unless absolutely necessary.

At 10.30 we were told that Home Secretary Charles Clark would make a statement in Parliament, and just before noon he came into the chamber looking very grave. Normally the Commons is fairly noisy, but while he was speaking you could have heard a pin drop. And then something rather magnificent happened. One by one, the leaders of every other party rose to their feet and pledged their support. Party differences were forgotten, and everyone united against the terrorist threat. I wish MPs could behave like that more often. 

Everyone left the chamber determined not to let the terrorists win, and to get on with work as normal. The scheduled debates for the day (on defence, appropriately enough) went ahead as planned, and the phones slowly started working again.

I left the Commons just after 4pm. London was eerily quiet. The tube was closed and there were no cars, buses or taxis to be seen. The only things moving were people – thousands of us, walking home. It took me over an hour to walk from Westminster to Paddington station and all the way I was surrounded by a quiet, determined, steadily moving mass of people. It was like leaving a football match or a rock concert, except for the silence. But although no-one said anything, we were all thinking the same: sympathy for the victims and their families, and determination not to let the terrorists win