Police have been using it in London for several years, mostly at protests, but also in other 'test' deployments. They are currently required (it seems) to place signage around the catchment area to notify the public that facial recognition is in progress. Private companies may well have been using it for longer in their shops without having to notify anyone. Sainsbury's, for instance, quickly attracted suspicion that they were doing trials of it at certain locations.

Sainsbury's and B&M and a couple of others use Facewatch, I think.

A very badly run system, but alas no better or worse than USA stores and malls are doing.