"Police stressed that the ambitious exercise had been planned since January, but it will take on extra significance after the deadly shootings in Tunisia."
Met Police Commissioner, Sir Bernard Hogan-Howe, said: 'The threat level for terrorism has been raised over the last year and it is vital that we train and we learn.'
'Today's exercise will test our people in how to respond to a terrorist threat and we will learn from the mistakes that we are bound to make today.
'It's best we make them today in an environment were we don't have terrorists, than make those mistakes when we do.'
The rate of terror-related arrests has increased in the last year, he said to the point where one person is caught every day.
Obviously, not all of the above scenes are taken from yesterday's Operation Secure Tower - but what can we learn from a close study of them...?
Ketchup Caddy, Centre-stage.
Why is there no-one in this area at all for 100 feet on either side of the "bomb"?
(It's not a bomb, it's pyro)
Who has thrown up this cordon?
(it's not the Police)
What is the blue scaffolding and the lightweight wooden fencing for?
The London Bombs, The
Rogue Network And Iran
By Webster G. Tarpley