In a checkin queue at LAX
I was flying back from a trekking holiday in California that day. We were all standing in the checkin queue reading the papers, which were all about how London had got the Olympics. We found out what had happened from an Aussie family behind us in the queue. I think we spent the rest of the time at the airport trying to get in contact with friends in London, but of course texts were taking forever to get through and I didn't get replies from most of them until we landed. One of them had a lucky escape by getting an earlier train than usual.
It felt like the opposite of 9/11, where we watched everything happen in horrific realtime. On 7/7 it was just bits and scraps of information trickling out. Thankfully all my friends were fine, although one would have probably been on one of the tube trains if he hadn't changed his routine that day. So very lucky.