A USB device, containing 2.5GB of confidential Heathrow security data, was reportedly found lying in the street in west London. The USB device, which was reportedly unencrypted, contained sensitive information about the security measures taken to protect the Queen, cabinet members and foreign dignitaries.

The storage device also reportedly contained information about CCTV camera locations, timetables of security patrols, types of IDs required to access restricted areas and more. The USB device was found by an unspecified man in Ilbert Street in Queen's Park, according to a report by the Sunday Mirror.

The device allegedly contained 74 files, totalling 176 documents, including images, maps and videos. Some of the files were allegedly marked "confidential".

It is still unclear as to how the device ended up lying about in the streets of London. It is also unknown as to why sensitive security information was stored on an allegedly unencrypted device. IBTimes UK has reached out to Heathrow for further clarity on the matter.

"We have reviewed all of our security plans and are confident that Heathrow remains secure," A spokesperson for Heathrow said, The Guardian reported. "We have also launched an internal investigation to understand how this happened and are taking steps to prevent a similar occurrence in future.

"Heathrow's top priority is the safety and security of our passengers and colleagues," the spokesperson added. "The UK and Heathrow have some of the most robust aviation security measures in the world and we remain vigilant to evolving threats by updating our procedures on a daily basis."