The Data Protection Act restricts employers from using covert audio or video monitoring in areas which workers would genuinely and reasonably expect to be private. This would cover places such as toilets, changing rooms, and private offices.
There may be extremely rare exceptions to this, in cases of suspicion of serious crime, but if your employer is using this justification, they must have very good reason to suspect serious criminal activity and should have a clear intention to involve the police in the matter. They should also take care to ensure that any intrusion into such private spaces for surveillance purposes is as restricted as possible.
