When is a nutter not a nutter, but a politically motivated terrorist? And are those two states of being always mutually exclusive? Or are they always the same thing?

That first question was asked, in a fairly gentle manner, by a Muslim mate of mine on a social media site. The thread had been about the murder of the Labour MP Jo Cox — and my friend was a little surprised to note the ease, if not eagerness, with which other commentators were ready to describe the alleged murderer as being simply a ‘loony’.