London Fire Brigade has warned residents near the Docklands not to be alarmed by the number of response teams in the area, as part of it's largest ever training exercise. Two hundred and twenty emergency services teams are there to test the response to an air crash.
The scene has been simulated with a real Boeing 737 aircraft, buried in tonnes of rubble. One hundred actors are playing the part of casualties.
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David Cameron said the Met proved it can "do more with less" and declined to criticise the Mayor of London for his water cannon spend.
A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.