Quarrels between neighbours are the worst. Neighbours sometimes obsess over trivialities – small irritations being blown up into big grievances. Until the tragedy in the English Channel last week, in which 27 refugees drowned while trying to cross in an unseaworthy rubber boat, relations between Britain and France had something of the school playground about them. The Channel Island authorities had failed to grant French fishermen as many licences as they wanted. Britain wanted to plant British police officers on French beaches, so infringing French sovereignty. Even after the loss of 27 lives, the French were piqued that Boris Johnson posted a point-scoring letter he had written to Emmanuel Macron on Twitter.