Ex-shadow home secretary welcomes move and says equipment will prevent repeat of controversies such as the Plebgate row

David Davis has welcomed the introduction of 500 body-worn cameras to police officers across London, noting that the Plebgate controversy could have been avoided if armed officers on Downing Street had been wearing them at the time.

The former shadow home secretary and senior Tory MP said they should be given without delay to every officer in Britain.

"If there's a disputed event between the police and public there should be video evidence available and if it's not there then there will be an assumption that it's not been provided, that the police are culpable," he said.

"Plebgate is the obvious case. Had it been recorded then the dispute wouldn't exist. We wouldn't be arguing about who said what."

The Plebgate row centred on an altercation in which former Tory chief whip Andrew Mitchell was accused of calling officers on the gates of Downing Street plebs – a claim he strenuously denies.

Davis added that footage recorded by the body-worn cameras would have spared Scotland Yard from a "crisis of ethics" triggered by controversies including the shooting of Jean Charles de Menezes, the death of G20 newspaper vendor Ian Tomlinson and the killing of Mark Duggan, which sparked the London riots. "In each case there wouldn't have ben any dispute over the facts," Davis said.

"It's an extremely good idea. Everyone will be a winner. I think it should be introduced to every police officer in Britain, with the exception of approved covert or undercover officers."

In a round of television interviews on Thursday morning, the Met commissioner Sir Bernard Hogan-Howe admitted the cameras could have helped in the Duggan case.

He told BBC Breakfast: "I think as we saw in the recent incident - fairly recent incident - regarding Mark Duggan, there was a great dispute about what Mark Duggan was holding at the time he was shot, and this hopefully would have helped to resolve that."

If officers are found to regularly fail to switch on their cameras when they should do it will be treated as a disciplinary offence, he added.

He said the cameras would "capture the reality of some of the horrible things we have to deal with from time to time".

Officers in 10 London boroughs were on Thursday given the body-worn cameras – roughly the size of a cigarette packet – in a £815,000 trial billed as the world's biggest. To mark the start of the trial, the Metropolitan police released graphic footage of a domestic violence incident in London earlier this year. The footage shows the victim bloodied and emotional as her partner is dragged out of their flat, where blood is smeared across the walls.

The assailant later admitted the assault after being shown the video footage and was jailed for five months in February.

Police chiefs believe the cameras will result in a sharp increase in prosecutions and convictions. Hogan-Howe said the cameras would result in speedier justice for victims, particularly in cases of domestic violence.

He said: "Body-worn video will not only help us fight crime and support victims but help the Met to be more accountable.

"Our experience of using cameras already shows that people are more likely to plead guilty when they know we have captured the incident. That speeds up justice, puts offenders behind bars more quickly and protects potential victims.

"Video captures events in a way that can't be represented on paper in the same detail 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.

"I believe it will also show our officers at their best, dealing with difficult and dangerous situations every day but it will also provide clearer evidence when it's been alleged that we got things wrong. That has to be in both our own and the public's interest."

Firearms officers will test the cameras in their training environment in Gravesend, Kent, with a view to wearing them on duty if the pilot is a success. The trial will see a total of 500 cameras distributed to officers in 10 London boroughs, including Camden in the north of the capital and Lewisham in the south-east.

Speaking ahead of the trial, Metropolitan police chiefs said the move would aid transparency in the force following public criticism over its handling of the Duggan shooting. A jury at the inquest into the 29-year-old's death found he had been killed lawfully by a police marksman, despite also finding that he was not carrying a gun when he was shot.

A number of forces are trialling or planning to introduce body-worn cameras – including Hampshire, Staffordshire and Humberside – but there has been little empirical research on the success of the small pilots in Britain. Police commissioners have pointed to a year-long trial in Rialto, near Los Angeles, where complaints from the public dropped by 88% and use of force by officers fell 60%.

• This article was amended on 9 May 2014 to give the correct cost of the London trial.