The technology will improve, as will the ratio of false positives to real identifications, so that part doesn't worry me much. Eventually this will likely be a very efficient system for solving and preventing crime. Overall I'm not really worried about this development in a stable and functioning democracy like the UK.

There's definitely potential for abuse though, and I assume repressive regimes all around the world are working on their own versions of this technology, aiming to use it to quell political opposition or moral delinquency.