Testing alarm systems
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Diamond Heist: Alarms

Declan Lawn investigates one of the most audacious diamond heists in British history. Just how did a six-man gang break into a vault in London's Hatton Garden and escape with the contents of safe-deposit boxes estimated to be worth millions? Here, Declan asks questions about how secure the building was.

'What I learned re-tracing the Hatton Garden robbers' footsteps'

Britain's Biggest Diamond Heist? is on BBC Two on Sunday 26 April at 22:00 BST or you can catch up on BBC iPlayer

  • 26 Apr 2015