Boris was right to say that banning the burqa in public (as has happened elsewhere, most lately in Denmark) is wrong. Likewise, it is not unreasonable to expect the veil to be removed in cases where identifying the person is required.
For example, I read recently about a hard of hearing older woman requesting a Muslim shop worker to raise her veil so she could see her lips so that she could . (Reasonably enough, this request was acceeded to.) So - no pun intended - it's not always black and white.
Alas, Boris then descended to ridiculing Muslims by using such terms as "letter boxes" and "bank robbers". Having shown a little statesmanlike gravitas, he then started using the language of the bigot. It's one thing for the man in the proverbial "four ale bar" to resort to such speech, although it's truly deplorable in any circumstance, but this is a man who has held one of the great offices of State in the United Kingdom and who probably still aspires to becoming Prime Minister.