A passerby found an USB stick containing unencrypted counter-terrorism information, as well as details on police officers on the pavement outside a Manchester police station.

According to the The Daily Star on Sunday, which originally reported the incident, the memory stick is branded with the Greater Manchester Police (GMP) badge as well as the initials GMP POTU, which stands for Greater Manchester Police Public Order Training Unit.

Given the nature of the files stored on it, the newspaper concludes that it likely belongs to a high ranking GMP officer within this unit.

One of the documents is entitled "Manual On Guidance Of Keeping The Peace" and describes crowd control tactics and methods of handling riots, public disorder or violent individuals.

There is also a wealth of information pertaining to counter-terrorism training, such as methods of responding to attacks with petrol bombs, blasts, instructions on using firearms, water canons or tear gas.

The over 2,000-page manual comes with diagrams of crowd control scenes and tactical deployments and was produced by the National Police Improvement Agency.

The USB stick also contains a list of police officers' names, ranks and the division they operate within, the kind of information that can be very dangerous in the wrong hands.

The 34-year-old businessman who found the device and took it to the newspaper prefers to remain anonymous.

"We are aware of an article relating to the finding of a memory stick belonging to GMP by a member of the public," Superintendent Bryan Lawton, of GMP's Specialist Operations Branch, told The Press Association.

"We are currently looking into who this device belongs to, what information is contained on it and the circumstances surrounding its loss," he added.

Of course the obvious question here is why was the data not encrypted, which should be standard policy for any memory stick containing this sort of sensitive information.