LONDON — British ministers have been laying the ground for Keir Starmer's handshake with Xi Jinping in Beijing this week ever since Labour came to power. In a series of behind-closed-door speeches in China and London, obtained by POLITICO, ministers have sought to persuade Chinese and British officials, academics and businesses that rebuilding the trade and investment relationship is essential — even as economic security threats loom. After a “Golden Era” in relations trumpeted by Tory Prime