January 12 1918. The world is at war. In Washington, the British ambassador to the United States, Sir Cecil Spring Rice, writes a letter to a former US secretary of state William Jennings Bryan. In office, Bryan had worked tirelessly to keep the USA out of the war, crossing swords with Spring Rice. But the ambassador is effusive about Bryan and the USA in general. “One thing is absolutely certain: in no other country can an Englishman make such friendships.”

He encloses a poem he had written “as a sort of spontaneous outpouring”. The first line is “I vow to thee my country, all earthly things above”.

I had no idea that one of our nation’s favourite hymns began life as part of US-British diplomacy until I came across this letter in a book of Spring Rice’s diplomatic despatches. My grandfather had bought the book perhaps out of loyalty – Spring Rice was his wife’s uncle – rather than interest: the book was unread, and many of the pages uncut. Reading it armed with a pair of scissors, and with Trump, Ukraine, and tariffs ringing in my ears, I was taken back to a world that had disappeared – and yet is eerily familiar.