The origins of the Shia-Sunni divide are so arcane that, let alone non-Muslims, even many ordinary Muslims will struggle to explain if you asked them. It’s not surprising, therefore, as John McHugo points out that until not long ago this ancient dispute was “virtually unknown” in the West outside specialist academic circles.

Nobody really cared, or attached to it the kind of significance it has come to assume in recent times. It received “almost no attention” during India’s Partition debate” and was “clearly of little significance”, ...