London Metropolitan Police is about to become the police force with most officers wearing cameras, in the world.

Mayor of London Boris Johnson has announced that London police will be given around 20,000 cameras to be worn by officers. The cameras have already been in a stage of testing for the past year.

The plan was to distribute the extra cameras over the next decade. This has now been moved up so the 20,000 cameras will be active by the end of March 2016.

From the testing so far the cameras have been generating about 6,000 video clips per month.

The cameras record a rolling 30-second loop which gets updated and deleted on the fly, unless the officer presses record. Once record is pressed the initial 30-seconds of video is kept and attached to that recording too.

According to City Hall the cameras haven been useful in situations, "where trust is key and police behaviour is under scrutiny, for example in stop and search, and where early evidence and victim testimony is critical such as in cases of domestic abuse."

Met Commissioner, Sir Bernard Hogan-Howe, said: "[The cameras] will […] improve public scrutiny of how we carry out our role. That is a vital part of being an accountable police officer.  It is also an essential tool in gathering evidence of offences."

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