Six degrees of separation

Here’s a statistical freak. The chances of knowing anyone directly affected by the terrorist bombs must be vanishingly small. Yet I discovered on Thursday that a woman I know slightly from work had been on the tube train that had been bombed at Aldgate. (She suffered from smoke-inhalation, but is basically ok). Then I find that a friend of my son had been on the bus that was bombed in Tavistock Square, but had disembarked a few minutes earlier, having concluded that it would be quicker to walk. And now I discover that the sister of a colleague had been on the Aldgate train, and had stayed to help the wounded.