The security operation that will take place during the Olympic Games this summer will be the largest carried out in peacetime.
Thousands of new recruits are being trained to operate x-ray machines, search vehicles and stand guard at Olympic venues across the country.
Today, ITV News was given exclusive access to the training centre in East London, where up to 800 people per day are undergoing intensive lessons.
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Authorities have warned that the death toll is likely to rise as much of the building is yet to be searched.
The PM will sound out the possibility of new free trade agreements with Gulf states for once the UK has left the EU.
In the unexpected announcement on Monday, Mr Key said it was the "right time" to leave politics.