Heywood was Gu’s business partner and reputed to also be working for MI-6.
MI-6? I suppose that, even if he was not working for them initially, he would have been recruited eventually. MI-6 cannot miss such a golden opportunity. In a communist country, there is no better way to can a powerful figure than tying him with foreign espionage. Many powerful figures in various communist countries had been purged ostensibly for being foreign spies.