Bromley police officers will see a large scale roll-out of body-worn cameras from today.

Cameras will be issued to all 32 boroughs and several frontline specialist roles, including overt firearms officers.

Although the cameras will be attached to officers' uniforms, they will not be permanently recording to ensure officers' interactions with the public "are not unnecessarily impeded", according to a Metropolitan Police spokesman.

Members of the public will be told they are being recorded "as soon as practical", with the camera flashing a red circle and beeping when it is activated.

Met bosses argue the cameras have already shown they can bring about "speedier justice" for victims.

In particular, bosses say they have proved successful in domestic abuse cases where there has been an increase in guilty pleas from offenders who know they have been recorded.

The roll-out is part of a three-year contract worth £3.4m with police technology firm Axon Public Safety UK, who are supplying the Met with 22,000 cameras.

Footage is subject to legal safeguards and guidance, and is automatically uploaded to servers once it has been docked, unless it has been marked for police evidence.

Police commissioner for the Met, Sir Bernard Hogan-Howe, said: "Our experience of using cameras already shows that people are more likely to plead guilty when they know we have captured the incident on a camera.

"That then speeds up justice, puts offenders behind bars more quickly and most importantly protects potential victims.

"Video captures events in a way that can't be represented on paper in the same detail, a picture paints a thousand words, and it has been shown the mere presence of this type of video can often defuse potentially violent situations without the need for force to be used."