Must be a truly dangerous place...
https://web.archive.org/web/20100824175032/http://fitwatch.o...
This sort of thing, deploying facial recognition systems in the street in the hope of finding someone, is much more insidious. Technically you can choose to bypass it, or pull something over your face, but that's more or less guaranteeing that you'll be stopped and questioned as to why you're concerned about it.
Sadly the UK never met an authoritarian they didn't like (apart from Hitler, so long as you're not as bad as Hitler himself you're good though). When surveyed the British public will call for banning basically anything they don't like, even if it doesn't impact them at all.
But it's not you that decides that what you are doing is harmless. It's what the authorities decide; and that can be quite different from what you or other people deem "nothing to hide".