Actualy I knew this was coming long ago!
(I really thought they would ban any form of disguise that allowed someone to hide from a camera.)
A society that comes to rely and depend on a sense of security provided by the loss of outdoor privacy via CCTV everywhere, cannot allow things which allow people to escape those prying eyes.
That means all methods of concealment or disguise of ones face or personal features must be outlawed.
That is especialy true with things like facial recognition software.
No honest person needs to hide thier face. Only those with something to hide would want to legaly be able to cover thier face.
The goal is to be able to point a camera at any person walking down the street (and everyone in London is on a CCTV camera several hundred times a day), and have facial recognition give you a very narrow list of possibilities of identity, some of which won't be from the area further narrowing likeliness of who it is.
It would probably be easier to just force everyone to wear bar codes though, and make it illegal for anyone to walk around without one.
They could be tiny tags, or even RFID chips. Not wearing one could be made a felony, and cheap checkpoints, cheaper than a CCTV camera could be installed throughout the city tracking and monitoring everyone. Linked with cameras it would be obvious to anyone at the monitoring station who everyone was on the camera. They could even have a map overlay of the city showing every person in the city at any time by knowing the last RFID scanner anyone walked past.
First it could be passed to keep track of criminals, implement all the necessary hardware, work out any bugs etc. Then some serious crime can be used as an excuse to motivate the public and legislators to make everyone "safer" by requiring everyone to have such a tag.
It is not science fiction, it could be easily and cheaply implemented, and it would not really be an inconvenience to anyone on a daily basis.
It is no more complex than automated toll booths which work on the same technology.
Perhaps after it has successfuly been implemented and demonstrated in the small UK test environment our own government can make us safer in the same way!
Of course our own government still has more serious things to restrict first, like powerful firearms that still pose a threat.
(Sarcasm. I do not condone the loss of freedom or privacy, especialy when more people were killed by thier own governments in the 20th century than in all wars combined.)