Is this all it is? Same effect as having a CID officer in an unmarked car with a flask and an empty 2.5 litre coke bottle?
There is not much to be learned about pervasive, 24/7 dragnet surveillance from comparing it to one officer in one location. They are completely different concepts with different consequences. An officer can track a few people for a short time. Stingrays and the like can build an ongoing narrative about everyone who passes them, criminal or innocent.
Factual question: What can Stingray collect? Is it 'device number NNN was in my capture range at 095627 on June 11th 2015' and then the local police have to analyse the data over time? Or can they get more precise location information by triangulating with several Stingrays?
Factual Answer: Logging of IMSI (sim card ID) and IMEI (phone ID). Potentially also logging pTMSI (temporary IMSI used over the air), MSISDN (phone number).
You should be able to get good idea of the handsets distance from the station based on timing delay.
As it's acting as a full fake site it could potentially be used to deny service, drain the battery, MiTM outgoing SMS & phone calls, possibly use the E911 provision to request GPS location from the handset too...
So My Friends in the Met could have a few of these things at sensitive points, and sit there and collect data along the lines of name (via phone number), time, date, location, device ID. Running this for some weeks would allow them to build up a list of people traversing a certain route daily.
Phone/sms could they decrypt the phone calls with the device ID? Seems a lot of data to collect given the number of people passing through many locations in central London.
There is not much to be learned about pervasive, 24/7 dragnet surveillance from comparing it to one officer in one location. They are completely different concepts with different consequences. An officer can track a few people for a short time. Stingrays and the like can build an ongoing narrative about everyone who passes them, criminal or innocent.