It winds me up that we are more terrified, as a Nation, of Islamic terrorists and the like who live in other countries and send the odd groups into our midst then we ever were of the IRA who lived just over the water! I do believe it is fear caused by Americans who never dealt with terrorism until 9/11 (God, I hate that term!) and now feel everybody is out to get them. I am not saying Americans are bad as I know we have some Yankee members, please don't be offended as the fear has been generated from on high. We dealt with terrorism for years and we just got on with our lives. By putting the terrorists on the news and showing them they are terrifying the populace, then they have won a small victory. The BBC never allowed Gerry Adams to speak on the TV, they dubbed his voice over. It was ridiculous, but it was for a reason. They weren't given the impression that we were all sat at home filling our pants in fear. The lot today are, and we are reaping the reward for giving them so much attention.
As for a course, what will they do? Sit them on a bus and blow it up and then get the survivors to run to safety? Absolutely stupid idea. You cannot plan for every eventuality. If the proverbial hits the fan, get on your toes and away from it, but ensure you aren't getting bottle necked into a second attack. Take what is yours and go. If you work in London, stay away from public transport as that will probably be a target too. Move away from the attack but don't panic or else you may start the stampede. If one starts, get away from it as soon as possible so that you don't get injured. If you do walk into a secondary attack, there's not much you can do about it.