Live facial recognition trial at London railway stations yields one false alert after scanning 500,000 faces

Representative image

A six-month trial of live facial recognition at London railway stations cost British Transport Police (BTP) £320,786 and scanned more than 500,000 faces, but it produced just one alert from the police watchlist. That alert turned out to be a false identification, with no arrest resulting directly from the technology during the trial period. The findings were reported by The Guardian, which reviewed a freedom of information document obtained by Liberty Investigates. The trial ran between February and July 2026 and involved 18 deployments at some of London’s busiest transport hubs. BTP has since extended the programme, raising fresh questions about cost, accuracy, privacy and whether live facial recognition is proportionate for use across a public transport network.

How the trial worked

Live facial recognition cameras compare faces passing through a particular location with images on a police watchlist. The system is designed to identify people who may be wanted by the police or subject to court restrictions. The cameras do not treat every person as a suspect. According to former biometrics and surveillance camera commissioner Fraser Sampson, the system’s use depends on the composition of the watchlist and whether the people being sought are likely to appear at the chosen location and time. During the London trial, cameras were deployed at railway stations between February and July. More than half a million faces were scanned during those operations, while officers and specialist equipment were positioned at 18 separate deployments. The trial was intended to explore whether the technology could help identify wanted offenders and people breaching court orders. British Transport Police also said the system could support efforts to tackle violence against women and girls, particularly in transport environments where concerns about harassment and sexual offences can affect how people travel.

One alert, and it was wrong

Representative image from Canva

The technology produced one alert against a person on the police watchlist. Officers checked the result, but the individual was not the person sought. The alert was therefore classified as a false positive. No arrest resulted directly from an LFR alert during the six-month trial. The equipment hire and police staffing costs came to £320,786, while officers spent almost 100 hours supporting the operations. BTP said officers made other arrests during the deployments, including arrests linked to assault, theft, possession of an offensive weapon, public order offences and breaches of criminal behaviour orders. Police also located individuals wanted by courts and other forces. However, BTP acknowledged that these arrests did not result directly from facial recognition alerts. They were therefore excluded from the official LFR performance data. That distinction is important because it separates the general policing activity surrounding the trial from the results produced by the facial recognition system itself. The wider deployments may have helped officers identify or respond to other incidents, but the technology generated one watchlist alert, and it was inaccurate.

Why police are continuing the programme

Despite the limited results, BTP extended the trial for an additional four months. The extension expanded the deployments to include London Underground stations. The force said the first phase helped it understand how the technology could be used most effectively in a railway environment. It also said procedures had been refined around deployment locations, equipment, watchlist construction and operational safeguards. BTP reported that since the extension began, there had been three confirmed positive alerts. However, those individuals were later confirmed to be complying with sexual harm prevention orders or other court-imposed conditions. A positive alert does not necessarily mean that someone has committed a new offence. It indicates that the system has identified a person who appears to match an image on the watchlist. Officers must then verify the person’s identity and determine what action, if any, is appropriate. The force said watchlist growth had been deliberately controlled. It began with a smaller list while staff worked to ensure data quality, governance and safeguarding arrangements were robust.

Concerns about accuracy and proportionality

The trial has renewed debate over whether live facial recognition is appropriate for crowded public spaces. Critics argue that members of the public are being scanned without individually consenting, even when they have done nothing wrong. The technology also processes biometric information, which is considered sensitive personal data. The fact that one alert was incorrect during the trial has raised concerns about how false matches can affect people who are stopped, questioned or exposed to police intervention, as per the report.

A growing use of facial recognition

More than half of police forces in England and Wales have now used live facial recognition on public streets, according to an analysis by Liberty Investigates. The technology is also expanding in London. The Metropolitan police and the mayor’s office announced plans for fixed facial recognition cameras in the West End. Mayor Sadiq Khan has confirmed that the technology will be used on the newly pedestrianised Oxford Street. The expansion has taken place while Parliament continues to debate the legal safeguards surrounding artificial intelligence and biometric surveillance. A recent report from the Joint Committee on Human Rights described live facial recognition as a particularly clear example of the risks created by AI. Bell Ribeiro-Addy, the Labour MP for Clapham and Brixton Hill, called the technology a serious invasion of privacy and said its rollout should be suspended until stronger safeguards and a clear legal framework are in place.

What happens next

The BTP trial is continuing, but its early results have made the debate more complicated. Police have said the technology can help identify people who pose a risk to passengers and staff, while critics argue that the financial cost and privacy implications require much stronger evidence of effectiveness. The programme’s next phase will provide more data, particularly now that London Underground stations have been added. Officials will need to assess not only the number of alerts, but also their accuracy, the number of arrests that directly follow them and the impact on people who are wrongly flagged. For passengers, the issue is not simply whether a camera can recognise a face. It is whether the system can do so accurately, fairly and under rules that protect people who are not suspected of wrongdoing. After scanning more than 500,000 faces at a cost of over £320,000, the first six months produced one alert and one false identification. The extended trial will determine whether that result was an unusually weak beginning or a sign of the practical limits of live facial recognition in Britain’s busiest transport spaces.

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