Tony Blair is on the edge of a hostage crisis similar to when diplomats were seized in the US embassy in Tehran in 1979.
Today it has emerged that both the UN Secretary-General and EU foreign policy chief Javier Solana have held talks with Iran on the issue. But Iran has refused to release the 15 British personnel until Britain apologises for the alleged incursion.
The parallels with the holding of 66 Americans in 1979, most for 444 days, are ominous. For a few days the world watched while Ayatollah Khomeini, the leader of the Islamic revolution, decided whether to back the actions of the students. Declaring it was a "second revolution", Khomeini smashed the hopes for any early resolution of that crisis.
Will Ayatollah Ali Khamenei, Khomeini's successor, see this as an opportunity to announce a "third revolution"?
The temptation is clear. Iran is under intense international pressure over its controversial uranium enrichment programme which it insists, implausibly, is for peaceful purposes. Domestically, Iran's economic woes are, perhaps only temporarily, alleviated by high oil prices. The ideologues still believe in the revolution, but many Iranians are just cynical.
For the moment Khamenei and the less powerful but noisier firebrand president Mahmoud Ahmadinejad are silent.
This is partly a reflection of the continuing Nowruz (Persian new year) holiday. It is also probably because each man wants to see which way the wind is blowing and how he can best use the circumstances. Humiliating Mr Blair, like President Carter 28 years ago, must be tempting.
There is little doubt the seizure was planned by Tehran rather than being the action of an impulsive local commander. A few days earlier, speaking of the impending United Nations Security Council vote that condemned Tehran for its nuclear stance, Khamenei had declared that such a vote would be "illegal" and that Iran's response could therefore be similarly "illegal".
The Foreign Office has tried being discreet. Bilateral contacts, except on the hostages issue, are suspended. The US has so far remained quietly supportive of Britain's diplomacy. This week one of America's two aircraft carriers in the Gulf skipped a planned visit to Dubai in a show of strength to Iran and support for London.
Now, via the UN as well directly on a bilateral basis, Britain could also reach out to the Third World. Such countries might be hostile to Britain's role in Iraq and closeness to Washington but they also value the UN.
But Blair's preference, indeed best hope, is probably the UN. After all, the seized personnel were operating under the mandate of a Security Council resolution. A non-nuclear resolution condemning Iran would shock the mullahs. But would it shock them further into or out of the crisis?
Tehran has to be convinced this is a predicament for Iran, rather than an opportunity.
Simon Henderson reported from Iran during the 1979 crisis. He is now director of the Gulf and Energy Policy Programme at the Washington Institute for Near East Policy.