Detective Chief Inspector Harry Hennigan has defended the decision by authorities to let a man out on day release from prison, who subsequently carried out a series of armed raids.
Sean Bradish was handed down two life sentences having already received one previously.
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The victim, a woman in her 40s from Hillingdon, west Londion, was conned into handing over the fortune to a man who faked his name.
Inspectors found a culture of bullying and major problems with poor ambulance response times at the trust, which is the biggest in the UK.
More than a tenth of the Piccadilly Line train fleet is out of action because of emergency repairs to damaged wheels.