The idea
If the UK was a person, it would be a paranoid schizophrenic. In london, there are orwellian posters with eyes hanging in the sky. There are announcements at every underground station, every train station, saying 'please attend your luggage'. The first problem with this is they are completely pointless. If an individual is hell bent on carrying a bomb in their briefcase, and is content blowing themselves and everyone else up….. well for a start, the unnattended luggage thing is useless when terrorists use suicide bombing techniques. So please, please quit this useless 'attend your luggage at all times message'. It has no effect except for making the whole platform shifty and suspicious. Don't you know a lack of trust makes people more untrustworthy? some basic metaphysics for you.
as a side note, if you want to beat terrorism, it will never happen by 'fighting' or 'locking down'. This will only make it worse, like the evil planet in the fifth element (a pop reference, but nevertheless a poignant one). The only way you can beat it is by being friendly and not attacking and threatening islamic countries.
Why is it important?
because the country's mental health hinges on relaxing a bit; because trustworthiness is born from a situation of trust, and vice versa; and because terrorism is an invisible enemy that roots from a hatred of western supremacy and control for hundreds of years.