By Andy Silvester How you doing, my old China? That was certainly the tone of the UK’s attitude towards Sino-British relations when the current foreign secretary, David Cameron, was Prime Minister. He even took a confused-looking Xi Jinping for a pint in the Cotswolds. As yesterday’s parliamentary announcements made clear, things have changed. China’s cyber attack on the electoral roll is one of the most significant in recent times, even if the actual information harvested can hardly be described as ground-breaking. But it does point to the constant, low-level state of war in which we are now …