That's exactly what I did, I used to get the Piccadilly line from Kings Cross going south around the time the bomb went off. The trains on that line at that time are really packed, about 4 to 5 people per m2, I can only imagine what it must have been like down there. But, I was 10 mins late that day and couldn't get on the tube to connect at Kings Cross. People were running out of my normal station but I ignored that and walked down to Kings Cross thinking 'stupid Northern Line I'll get on there'. When I got to Kings Cross there were lots of people milling around and walking away from there, I think I asked someone and they said the station was closed. So I just got on a bus on Euston Rd and went to work as normal. I bumped into a colleague on the bus and she said she had been walking past an air vent outside Russell Sq station when there had been a huge inrush of air and a deep rumbling sound. I remember saying to her that it was probably just the power supply going out, maybe a transformer explosion or something (we had just been discussing mitigation of transformer explosions at work a few days before). Obviously, it was a weird day at work, nobody did anything really. It was too far to walk home, I ended up getting 5 different busses, partly because the service was all over the place and partly because I had to get off one because I thought someone looked suspicious. I grew up in London and the three lines and the bus route that got bombed were ones that I had used regularly all my life, I took it quite personally that they had attacked 'my places' in 'my city'.