“Death to England!” reads the Farsi scrawl above the picture of the Queen in Britain’s embassy in Tehran. Four years ago, a pro-government mob ransacked the building. Iran is perhaps the only place left where Britain still outranks the United States as the most hated Western power, and the ayatollahs rarely miss an opportunity to stir up crowds against “the Old Fox.”

Last week, the embassy re-opened, the UK Government having decided, in a forgiving gesture, to undertake the cost of the repairs itself. Among all the vast implications of Barack Obama’s Iran deal, the reopening of one diplomatic mission may seem a small thing — but diplomatic missions matter.