We have had a number of thefts from staff bags in a staff room (it is a retail outlet so staff have to keep all their personal belongings in this room). We do not currently have CCTV but are considering installing it (for various reasons) and will be informing staff generally that we are putting it in and why. The question is can we install a hidden camera in the staff room without explicitly telling them that we are doing this? We obviously want to catch the thief but if we tell everyone about the camera, they will just stop and we will never know who it is. The other cameras will not be hidden.

Any thoughts would be appreciated.