Found this which I think has probably been mentioned before(?). It’s a job advert dated Oct 2006 for Network rail and I believe that the railways are the most likely customer for the 100000 camera tender due to the high density of camera’s required. (Unlike road tolls)
“Network Rail is also about to commence single option development of a major national CCTV enhancement project at all Network Rail managed stations. This project will include installing CCTV to give coverage to Transec requirements with associated equipment rooms, monitoring facilities and data storage provision.”
Not sure what "single option development" means????
Indigo also have previous experience in this sector with the Dutch railways system.