Last month, Mr Kim Darroch, the British ambassador to the United States, was forced to resign following the leak of a cache of British cables in which he called President Donald Trump "insecure" and his administration "inept" and "dysfunctional". The incident placed a rare spotlight on how diplomats communicate with their colleagues back home.

But perhaps equally interesting - though often overlooked - is the bizarrely baroque, exceedingly polite and occasionally menacing writing style that diplomats from different countries use when communicating with one another.