Mr Q
Tell someone infact tell two people incase the first one is stupid.
This is a serious matter and its better to have said something and found to be wrong than watching it on the news when you get home.........if you get home that is.
I do it all the time and the reaction is anywhere between apathy and action. Where i find the former i kick them until they do something. I now sit a the pointy end and somehow it all feels a little more critical to be aware.
Just re-reading my post.... every intelligence agency is probably looking at it too, loads of 'key' words like bomb, Heathrow, security
Hopefully they are and have learned something....hopefully.