Our threat in the UK is slightly different. Your average muslim over here straps a rucksack full of explosives on his back and gets on public transport. I have written a letter to my member of parliament with a suggestion. At airports we now see facial recognition technology. A much simpler device could be used on the transport system. Just a gate with a skin colour reader.
If you are white you simply walk through.
If you are very black you walk through (almost all of the menial staff and toilet attendants are black so we need them)
If you have dirty coloured brown skin then the gate closes and alarms go off.
A quick interrogation and a cavity search and then they are free to pass through. Everybody should be happy with this system. Anybody who complains obviously has something to hide.
I have not had a response from my MP yet but I will keep you updated.
YIC
Jack