And the answer is...

Pretty fucking soon, in response to my question on the 22nd of June, where I said:

I wonder how long it will be before people get suspicious of any closed containers and we all have to walk around with transparent rucksacks, spare tampons on display and all.

A reader's letter in the paper version of Metro this morning:

I was outside my building on Oxford Street this morning when a girl walks past wearing a huge rucksack. As everyone's been doing recently, I watched her as she walked by and stuck to the back of the rucksack with gaffer tape was a huge sign reading: 'I am going camping.'

But the definitely the scariest issue of the moment is the story of Jean Charles de Menezes:

Police have apologised over the death of electrician Jean Charles de Menezes, 27, who was shot when officers wrongly thought he was a suicide bomber... ...Police said his padded jacket had heightened suspicions about his journey. He was shot as he ran onto a train.
Heavy coats or clothing are often worn by suicide bombers in other parts of the world to help them disguise their bombs.

Despite what I'm sure that police forces around the world would love, running from a police officer is not a crime and certainly not an indication that one has been committed. I know if five plainclothed men started chasing me, I would panic and run like hell! And in that panic, adrenalin flowing and heart racing, I very much doubt I would hear or believe anyone shouting "Police!", nor would I stop until I found a uniformed police officer.

Let's see... what else did he do to arouse suspicion? He wore a padded jacket and his block of flats (not his specific flat!) was under surveillance. So he wore the wrong clothes and lived in the wrong place. His out-of-season padded jacket (he had recently spent eight months in Brazil with his father who was undergoing cancer treatment) wasn't suspicious enough to stop him getting on a public bus, but once he starts running for his life, he's clearly a suicide bomber and a threat to the public! Coz if I was a suicide bomber, I wouldn't just wait for the police to catch up with me and blow the living shit out of them, hmm?

But the story is still new - perhaps as all the facts emerge, we will find out that actually, the police made it obvious that they were officers before they started pursuing, and it won't have been their actions that triggered him into behaving strangely. Obscene as this may be to his family, I just hope that he was guilty of some crime that would justify his running from identified police officers - it means that there's some hope for the rest of us non-terrorists.