As an example, every morning of the working week there are thousands of commuters stood around on platforms at tube stations. It's an enclosed space that would give a maximum effect to an explosive device and also bring the city of London to a standstill. This would have far more impact than blowing up football supporters outside a stadium
Errr July 7th 2005 ? The biggest impact that had, was making intelligence better to prevent further attacks, and so far its worked.
A terrorist exploding himself amongst a crowd, has exactly the same media impact at a train station, on a train (London 2005, Madrid 2004), an airport (Belgium and others), or in a football stadium (none successful that I can recall), and to the terrorist it creates the same thing, terror, their whole reason for being a terrorist in the first place. The only target for a terrorist outrage is a large crowd with maximum collateral damage, it doesn't matter where it is.
Now the terrorist has a new tactic, drive a lorry into a crowd, its difficult to drive into a train station or an airport building, as measures were taken years ago to stop it, but other gatherings of people are easier targets. Yesterday it could easily have been the queues extending beyond the security cordon because of our inefficient searching routine. So, City, by doing this badly, have succeeded in creating a new target.
As I said earlier, our queues are being tagged as being for security reasons, but they're not, if they were they'd be effective, they're there to create an issue that forces people to turn up earlier, as people don't like queues, that is why they are coincidentally (yeah right) taking food and drink off people going in, to get them to buy it when they go inside earlier.