A few years back I worked for a while on the bottom floor of BMA House on Tavistock Square, London. My office overlooked the road.
Having read that the blood from Thursday morning's bus explosion splashed across the windows of the building (indeed, across the frontage of much of this magnificent building), I find it hard to get the memory out of my mind. The memory of being there at an event that I did not see. It is so very detailed.