http://www.guardian.co.uk/terrorism/...642233,00.html

Commuters face airport-style scans

Rail and London Underground passengers could soon face airport-style
scanning techniques under new anti-terror plans, the transport secretary
revealed today.

Alistair Darling pledged to reduce the risk of another terrorist attack
on London but admitted that security systems on rail networks would
never be as stringent as those in airports.

....

The new cameras are programmed to look for suspicious behaviour
patterns, such as one person standing in the same place for a
significant length of time,

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Perhaps he should use public transport more often...