france," he said, "but if the uk continues to act like this, there will be retaliation." the irritation on both sides of the channel shows no sign of fading and for boris johnson, a rumbling row with an important ally like france is not exactly helpfuljust when he's trying to achieve a far wider, grander aim — persuading all of his counterparts from right around the world that slowing down the changes to the climate is a non—negotiable whose time has come. it's not easy, though. some countries don't want to move as fast. the russians questioning the uk ambition for countries to absorb as much carbon as they emit by 2050. why do you believe 2050 is some magic figure? i want an answer because you're asking the question, being convinced that 2050 is non—negotiable. but the prime minister has regal backing and, for the heir to the throne, it's been a moment long in the making.