This rule also applies to lesser disputes. After Zimbabwe’s bloodstained election of 2008, Heidi Holland, the author of a study of President Robert Mugabe, tried to set up a back channel between her subject and the British government. As it happens, I once lived and worked in Zimbabwe, so she kept me informed about her efforts, while swearing me to secrecy. Tragically, Holland died last week, so I feel able to disclose her efforts to heal the rift between Britain and Zimbabwe. She offered the previous British government a channel to Mugabe, via a carefully chosen intermediary who had served as a Zimbabwean cabinet minister for many years before moving to Britain. But the idea fell at the first hurdle: the Foreign Office was not interested.