Could also be rephrased as "Do you mean that the all the CCTV surveillance in the City is decentralised and only accessible by warrant to each system owner?"
In the City, I can easily imagine there's still a single entity behind it, just one that's not accountable to the public. No idea whether that's the case, though.
Anyone running CCTV needs to register with the Information Commissioner and there are some limits to what can be done with the footage or how long it can be kept for.