It is shocking to see the Tory leadership turn against the liberal approach of Boris Johnson

Ruth Davidson said this week that whenever in history men had made “sweeping statements about what women should or should not wear”, it had not gone well for them.

She is probably right, but for some reason she used this to attack Boris Johnson. Who is it that decrees, in the name of God, what Muslim women should wear, telling them to cover their faces completely? Men: always and everywhere, men. In places where such men have been in charge – places ruled by the Taleban or Isil, for example – they have killed women who refuse. Why did she attack their critic, not them?

Ms Davidson also asked: “Would you ever write in the Telegraph that you should have a debate about banning Christians from wearing crucifixes?” She thought the debate about burkas was “the same argument”. The comparison is weird. A crucifix can be worn equally by either sex and does not prevent other people seeing you.

Seeing is believing. All societies need trust. A multiracial, multi-faith society makes trust harder to achieve, so we need to work harder to secure it. It is almost impossible to trust people whose faces you cannot see (and by the way, women thus dressed rarely speak to strangers, so in practice you cannot hear them either).

At worst, face-concealment implies evasion and/or ill will – like the masks worn by terrorists, animal rights protesters and (see Boris) bank-robbers. Obviously, this does not apply to most women wearing the burka, but the problem of deliberate invisibility remains.

It amounts to a passive-aggressive statement by the wearer that she – or, if she is under duress, her male controller – wants no part in our wider society. Islamists cultivate this apartness, trying to cut Muslims off from their fellow citizens.