Does Jonathan Powell really want to negotiate with the Islamic State?

I think I’ve finally worked out the time-honoured Jonathan Powell formula for promoting a new book: take which-ever group constitutes the most bloodthirsty terrorist organisation of the day — in this case IS, the warped Islamist force currently enslaving and beheading its way across Iraq and Syria — and create a media fizz by boldly declaring that sooner or later we’re going to have to negotiate with them.