No one has yet been able to answer that question definitively.
The ransacking certainly made some people feel good that they had humiliated the British.
But a true conspiracy theorist, of which there is no shortage in Tehran, would logically assume that the attack was an American plot, since the primary benefactor has been those in the United States who paint the Islamic Republic as untrustworthy and wish to rally the world against the regime.
Or, as The Telegraph of London put it succinctly in a headline, Iran has “scored a diplomatic own goal.” An own goal is a soccer term for when a player kicks the ball by mistake into his own goal and scores for the opposition.
Britain last week withdrew all of its diplomats from Tehran and 
Foreign Secretary William Hague said the raid was conducted by members of the Basij while the Tehran police stood by and did nothing as the Basijis poured across the embassy gates.
Hague said, “Iran is a country where opposition leaders are under house arrest, more than 500 people have been executed so far this year, and where genuine protest is ruthlessly stamped out. The idea that the Iranian authorities could not have protected our embassy or that this assault could have taken place without some degree of regime consent is fanciful.”
He said the raiders were members of the student Basij group recruited from Tehran campuses. “We should be clear from the outset that this is an organization controlled by elements of the Iranian regime.”
There was clearly coordination between the Basij and the police. The police did not stop the Basijis from overrunning the embassy. When the police eventually were sent in to clear the grounds, they were not seen to use any force, but were unusually gentle in asking everyone to leave and unusually patient in waiting hours for the grounds to be cleared.
The Dubai-based satellite television station Al-Arabiyya said that video taken at the start of the protest revealed that Gen. Reza Naqdi, the head of the Basij, was standing in front of the embassy. However, the Iran Times has not found any such video or still shots from it.
Who actually authorized the attack remains a mystery. Supreme Leader Ali Khamenehi has been completely silent. Many think he approved the attack. That is, however, only speculation.
President Ahmadi-nejad has also been completely silent about the attack in the week since it was carried out. But no one suspects him of being behind the assault. In fact, there is much speculation that he was the real target, not the British embassy. Many Tehranis believe the president’s enemies dreamed up the assault to embarrass him internationally and make it harder for him to execute any foreign policy initiative. Some cite the prospects of resumed nuclear talks and think the embassy attack was designed to make the West angry and less willing to negotiate.
There is an element in the Islamic Republic that has always believed that the best hope for the revolution is complete isolation from the rest of the world so that the poisons of western culture and thought cannot penetrate Iranian society. Some think that element was behind the embassy attack.
Very few seem to believe the simplest possible answer—that the raid was a product of the large number of Iranians who hate Britain and simply wanted to punish it. The main problem with that theory is that someone up high had to issue orders for the police at the embassy to ignore the basijis climbing the embassy wall.
The earliest and strongest words of support for the raid have come from Majlis Speaker Ali Larijani, who is strongly opposed to Ahmadi-nejad. That has fed the speculation that Ahmadi-nejad might be the chief target. Larijani said the attack was a genuine expression of honest Iranian fury at Britain for all the harm it has done to Iran.
He said, “How long must we endure the presence of the British in Iran … when they interfere with our national interests … and commit treachery against the Iranian people?” He damned “decades of domineering” actions by Britain.
But there isn’t uniform conservative support for the attack. Ayatollah Nasser Makarem-Shirazi went out of his way to criticize the attack. He called Britain one of Iran’s “oldest enemies,” but cautioned that “emotional actions beyond the framework of the law can … force us to pay a high price.” He speculated that anti-Iranian elements had infiltrated the demonstrators and provoked the attack in order to promote a foreign backlash against Iran. (There’s that conspiracy theory.)
And at Friday prayers, Ayatollah Ahmad Khatami instructed worshippers to chant “Death to Britain,” but then said: “I explicitly say that I am against attacking embassies and occupying them. Occupying an embassy is like invading a country and is illegal.”
Perhaps the most unique reaction came from Tehran Province Governor General Morteza Tamaddon. He simply denied that the embassy had ever been taken over and blamed the foreign media for inventing the story.
The task of cleaning up the mess was left to the Foreign Ministry. Foreign Minister Ali-Akbar Salehi flew to Germany for a conference soon after the raid and, according to a German Foreign Ministry statement, expressed deep regret at the attack and pledged to prevent any repeat. But he made those comments in private meetings.
The Foreign Ministry was caught off guard when Britain expelled all Iranian diplomats. It did not seem to have anticipated that as an outcome and was embarrassed. Fars news agency quoted an unnamed Foreign Ministry source as saying Iran would probably retaliate by expelling all British diplomats. But all British diplomats had been taken out of Iran before Britain expelled the Iranian diplomats because UK officials feared any diplomats left behind might be taken hostage.
Deputy Foreign Minister for Consular Affairs Hassan Qashqavi said the British were just being thoughtless and nasty because the expulsion of the diplomats meant the Iranians living in London could no longer receive any consular services. That was a bit of crocodile tears. While Iran and the United States have no relations, consular services are available to Iranians in the United States through a mission attached to the Pakistani embassy. Qashqavi did not express any sympathy for the Iranians who had given their passports to the British embassy to process for visas and who have now lost their passports.
No one has stepped forward to claim an organizational or leadership role. However, as criticism of the attack started to mount days after the raid, a statement was issued claiming to come from the organizers of the protest outside the embassy. It said the protesters had no plan to seize the embassy, calling the attack “spontaneous” and saying the students had merely acted out of “revolutionary rage.” However, an earlier statement from the group had boasted that the seizure of the embassy had succeeded in humiliating Britain in the eyes of the world. The change in tone appeared to reflect a growing view in Tehran that the raid was a very bad idea for Iran.
The police announced that they had arrested 12 men involved in the attack. They did not say what those men were charged with. The next day, the police said 11 of them had been freed.
No government has announced support for the embassy attack. Dozens have condemned it. Not only have both Russia and China been explicit in saying the attack was indefensible, but even countries like Vietnam and Mexico, which are normally silent about events so far away, issued statements of condemnation.
Germany, France and the Netherlands have recalled their ambassadors in protest over the raid. No other embassy staffs have been reduced thus far, however.
The British embassy sent all of its local staff home before the protesters formed outside the embassy wall, so none of the Iranians working there were present for the embassy seizure.
Ambassador John Chilcott said seven embassy staffers sent to the embassy residences in the Qolhak district were trapped and surrounded by invaders there and forced to sit in silence for about three hours, but were not physically assaulted.
He said the embassy and Qolhak grounds both have “keeps” where staffers can lock themselves away if the grounds are overrun. That was where most of the diplomats waited out the attack. He said nothing about the widely rumored tunnel to safety under a roadway to the Russian embassy just to the north of the British compound.
This was not the first attack on the embassy. In 1987, when Britain was accused of backing Iraq in its war against Iran, the embassy was attacked and Edward Chaplin, the charge d’affaires, was abducted and beaten, but quickly released.