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Olympic Games: Security tight ahead of London 2012

20 July 2012 Last updated at 19:46 BST

Military personnel have started to be deployed at key sites as final preparations for the London 2012 Olympic Games get under way.

An extra 3,500 troops were drafted in last week after security firm G4S admitted a shortage of staff, and a further 1,200 troops are on standby.

They join thousands of police officers who have long been working to ensure that the greatest sporting show on earth goes without a hitch.

Richard Bilton reports.

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