LONDON — At the King Ecgbert School in Sheffield, teens who go to the bathroom are never really alone — video cameras are inside all 12 loos.

Citing findings gathered via freedom-of-information requests, privacy activists Wednesday identified King Ecgbert as one of more than 200 high schools across Britain that have installed surveillance cameras in bathrooms or locker rooms.

The group behind the report, Big Brother Watch, said a powerful watchdog is needed to ensure that students' privacy is protected.

The report "will come as a shock to many parents," said director Nick Pickles. "Schools need to come clean about why they are using these cameras and what is happening to the footage."

Lesley Bowes, King Ecgbert's principal, argued that the cameras help keep her students safe.

"It's a way of safeguarding our children," Bowes said. She described her school's cameras — whose footage is reviewed only if there is suspicion of wrongdoing — as useful anti-bullying tools. And she rejected any suggestion that the recording captures the students' most intimate activities, saying the cameras monitor just the doors.

"The cameras are nowhere near the toilet cubicles," she said.

A total of 207 high schools across England, Wales and Scotland acknowledged installing cameras in toilets and changing rooms, according to Big Brother Watch, which sent freedom-of-information requests to nearly 4,100 schools in May. That's a conservative figure, according to Pickles. Nearly half the schools queried didn't reply by the deadline.

It isn't clear where in the bathrooms all those cameras are being placed, who is watching or whether any youngsters have been taped in states of undress.

The Information Commissioner's Office, an independent authority in Britain whose duties include promoting privacy, said recording in toilets or changing rooms is legal, but it is recommended that it be used only in the most exceptional circumstances.

By contrast, in the U.S., the use of video cameras in schools is generally not allowed in places where there is a "reasonable expectation of privacy," such as bathrooms and locker rooms, according to the Justice Department.

"The cameras for the toilets are strategically placed in the doorways and directed toward the washbasins to identify any students if there are any reported incidents in these areas," said M. L. Litton, principal of the Wildern School in southern England, which has one camera in each of its 12 bathrooms.

"The images are not looked at unless there has been a reported problem and all images are deleted after a maximum of 30 days," she added.

Why put cameras in bathrooms in the first place?

King Ecgbert, in Sheffield, is a relatively large, well-performing school whose glossy website shows modern classrooms lined with flat-screen monitors. Wildern specializes in the performing arts and is surrounded by a suburban neighborhood of neatly kept brick homes, many of them with a few cars in the driveway.

Although knife crime is a problem in urban areas, British high schools aren't blighted by the deadly gun violence that has prompted many U.S. counterparts to install airport security-style metal detectors at their entrances.

Both King Ecbert and Wildern said the cameras weren't meant to tackle serious problems, with Litton saying the cameras had mainly been installed to control "typical teenage stuff," such as smoking.

Over all, Big Brother Watch estimated that British high school students and staff are monitored by more than 100,000 cameras, with 90 percent of the schools surveyed acknowledging the use of some form of video surveillance.

That's a huge army of cameras — even by the standards of Britain, whose cities, towns and trains bristle with recording devices. Big Brother Watch cited previous research showing that there were more than 50,000 surveillance cameras controlled by Britain's 428 local authorities.

Pickles said he isn't necessarily against putting cameras in bathrooms, but argued that parents and children have to agree and there needs to be a robust watchdog authority to make sure youngsters' privacy isn't being invaded.

Bowes, the principal of King Ecgbert's, said she has received no complaints.

"Everyone knew about the cameras in the bathroom," said Jess Hogg, who graduated from King Ecgbert last year. In a series of Facebook messages, the 19-year-old said: "Personally it made me feel a little uncomfortable, but then safe at the same time.

"Uncomfortable because I didn't know where they were in the bathroom ... safe just in case (there) was any trouble in school."