....I can't quite see the connection between terrorism and retaliation on a football pitch.
This is a fascinating turn to the discussion, and one where I agree - almost - with Radamfi. Let's start here, and think why retaliation is punished more than the original foul. There is something about it that feels primitive, "an eye for an eye", and that flies in the face of civilised values. And, as we are expected to leave the enforcement of discipline on the field to the referee, so we should hand over punishment of terrorists to the law. It is under the laws of this country that they should be tied, and, at present, those laws do not allow killing as a punishment. So it is wrong, utterly, to say "they deserve death", or "string them up", because that flies in the face of our current civilised values.
Another question that leads on from this is whether anti-terrorist police should be armed routinely. There is an argument that suggests you should not give anyone a gun without expecting them to use it, authorised or not, especially in times of stress. But it unreasonable to expect the police to face armed terrorists without guns. This is a question of getting the balance right, and i would hate to get into the sort of "shoot first, question later" approach that we have seen in recent occasions in the US.
However, for the average person in the street, there is nothing we can do to counter terrorism that is not a normal part of being a good citizen; report crimes and suspicions to the police, keep calm in emergencies, and
carry on as normal - do not let terrorists terrorise you. In other words, turn the other cheek, as Radamfi says.
Fowler9 is right to point out the subtle balance between control and freedom. To my mind inappropriate control is a much worse danger than terrorism, but that itself can be found in employers monitoring Facebook, "offended" bystanders reporting private conversations, and over-officious guards, as much as in spooks and their bugs.