We are not yet approaching the level of the events of November 1979 when Iranian students overran the US Embassy and held 52 Americans hostage for 444 days. But the seizing of high-level local staff at the British Embassy gives this crisis its own flavour: in the 1979 Islamic Revolution the Iranians who worked at the US Embassy were left alone.

“We [Americans] were the targets,” said Bruce Laingen, 86, who was chief of the US mission at the time. Local staff “started disappearing into the woodwork — they went back to their homes. None, as far as I know, was imprisoned.”

There were about 30 local staff at the embassy, which the hostage-takers branded a “den of spies”. Many were Iranian Armenians; a few had been educated in the US.

Before the hostage-taking the embassy had been briefly overrun in February 1979, but for just six hours. During that episode one local staff member was injured and another man killed, Mr Laingen said, but the Iranian employees “stuck with us”. The violence was enough to have all dependants of embassy staff sent home, as the British have done.

Today the defunct US Embassy in Tehran houses a detachment of Revolutionary Guards and an anti-American museum. It is the scene of ritual and desultory anti-US protests on every November 4, the anniversary of its seizure. The sprawling compound was stormed after the US agreed to admit the Shah for medical treatment for cancer. Tehran, which suspected that the US was conspiring to restore him to power, saw this as a hostile act.

The seizure was a devastating blow for moderates in the provisional revolutionary government. Ayatollah Khomeini, father of the Islamic Revolution, endorsed the takeover more for reasons of domestic than foreign policy: it cemented the revolution for him and his radical supporters who did not share the moderates’ hopes of a liberal democracy and accommodation with the West.

Five months later Washington severed ties with Iran, which remain ruptured to this day.

The takeover, images of militant students burning the Stars and Stripes and US diplomats blindfolded and humiliated, and the rescue attempt by US commandos that ended in calamity in the desert, crippled the Administration of President Carter and was largely responsible for losing him a second term.

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