It appears as if the Metropolitan Police have simply decided that anyone who 'looks a bit shifty' deserves reporting:
http://www.met.police.uk/campaigns/docs/postcard.pdf
"Terrorists need recruits: Do you know anyone whose behaviour has changed suddenly?
Terrorists need places to live: Are you suspicious of your tenant or neighbours?
Terrorists need transport: Has a vehicle sale or rental made you suspicious?
Terrorists need storage: Are you suspicious of someone renting commercial property?"
Gee, that isn't at all vague. "Thou shalt be suspicious" doesn't exactly strike me as a very wise commandment to live by.
Scaremongering, and promotion of mediocrity, both in one go? Great PR tactic. Wonderfully ambitious.