I do wonder, though, just how any normal regulations can be made to operate successfully in this sort of situation. Mistakes were made, and I think that they will be made again. Can the normal precautions be enacted when the level of fear and heightened concern was as it was then? Did the victim run away because he knew that his illegal status might be the reason for the chase? And why do we still not have police radio systems which can work underground? The Tube was the threatened target.
I think Ken Livingstone's comments make a lot of sense.
"I think this is disastrous ... if an armed police officer believes they are in pursuit of a terrorist who might be a suicide bomber, and they start making calculations based on this - 'how's this going to be seen, am I going to be hauled off to court?'
At the end of the day, mistakes are always going to happen in wars or situations like this. The best you can do is to try to make the potential risk the minimum possible.