How do you verify who is coming through passport control if you cannot see the face. You cannot use a bank wearing a crash helmet, because it obscures the face.
Many west african countries are banning the burka on the grounds it represents a terrorist threat. These are largely Islamic countries!
https://www.telegraph.co.uk/news/2016/05/02/west-african-states-with-181-million-muslims-support-banning-the/

Far more worrying to me is the fact that the Met Commissoner Cressida Dick asked her officers to probe Boris Johnson's burqas comments.
To make this a very public announcement displays to me an overtly political stance. Does the police state soon follow?