London’s controversial gang database is almost a third smaller than it was a year ago, after the Met acted on concerns raised by two reviews.

The gang matrix was set up in the wake of the London riots in 2011 to monitor people involved with criminal groups in the city.

But an investigation by the Information Commissioner’s Office in 2018 found multiple serious data breaches on the database.

It was not clear how people were added to or removed from the list – and a Mayoral review found a disproportionate number of those monitored were of black or minority ethnic (BAME) heritage.

The Met has now removed almost 500 people with little or no evidence of gang involvement from the database, and says the majority have not committed a crime in the six months following their removal.

There are now 2,676 people on the list – and the proportion of BAME people added fell from 89 per cent in 2018 to 79 per cent last year.

Around 40 per cent of London’s population is from a minority ethnic background.

The number of children on the database has also fallen – from 14 per cent being under 18s in 2018 to just 6 per cent last year.

And the Met has now pledged to publish quarterly updates on the makeup of the database, with the Mayor committing to review the list annually.

Sadiq Khan said he reviewed the matrix because a “perceived cloak of secrecy” had caused “genuine community concerns” about its efficacy.

He said: “We are now seeing real progress with the Met acting on all recommendations.

“Our review showed that the matrix is a necessary enforcement tool for reducing violent crime in London, but it’s also vitally important that the police continue to evaluate and communicate how it is used.”

London Assembly Conservative group leader Susan Hall welcomed changes to the database, but raised concerns about the Mayor’s approach to violent crime.

She said: “There can be no doubt that the Gangs Matrix needs to be changed and reformed, but Londoners will naturally be worried that this move is yet another example of the Mayor going soft on crime.

“After all, it is Sadiq Khan as Mayor who has presided over a dramatic rise in crime and simply lost control of the streets.

“The Mayor’s number one priority needs to be to make London safe, and we will scrutinise these changes carefully to ensure that they don’t put more Londoners at risk of becoming victims of crime.”

Liberal Democrat assembly member Caroline Pidgeon also welcomed the changes – but questioned their timing given that the review of the matrix was published more than a year ago.

She said: “The simple fact is that this Mayor has not acted decisively enough on the issue of violent crime, and although I welcome the implementation of the changes, the Mayor has dragged his heels on this matter.

“I will be monitoring the gangs matrix closely following these changes to see if they make a substantial difference.

“If they don’t then I think the future of the tool should be considered.

“With the Met’s recent roll-out of Live Facial Recognition technology and use of questionable predictive mapping programmes by the force, it is still very clear that Londoners’ rights are being eroded.”