A thundering salavat, an invocation of God, his prophet and the imams, greeted Mr Khatami's more robust statements, followed by chants of "Death to America! Death to England!" As the crowd poured out, the worshippers expressed their defiance and anger at America's smaller ally, nicknamed "the little Satan".

"The British should get it out of their heads to act like they used to," said Hassan Asghari, an angry middle-aged man in a green felt jacket. "They have a very bad record here but must learn the colonial days are over. Now they're so weak all they can do is follow America."

Near the back of the courtyard sat President Mahmoud Ahmadinejad. He has so far played a low-key role in this crisis. There is a suggestion that he is still under instruction - reportedly issued two months ago - not to comment too strongly on foreign policy.

Many of the country's moments of national awakening have come in opposition to high-handed imperialism, most often by the British, and there is still a lot of bad blood here.

Britain and Russia occupied Iran in the early part of the 20th century. When Reza Shah refused to toe the Allied line in 1941 they occupied the country again, forcing him to abdicate. Iranians found themselves subject to foreign rule, culminating in the overthrow of a popular prime minister in 1953.

The arrival of British troops in the current conflict was seen by many Iranians in that context. The government has accused Britain of stirring up ethnic unrest, and the plight of Shia Iraqis since the 2003 invasion has not gone unnoticed.

Britain, or the "old fox", as it is often called, can stir up feeling across society. At yesterday's derby game between the city's two biggest football teams, the scoreboard bore anti-British slogans that were enthusiastically taken up by the crowd.

The crisis has escalated to near blanket coverage on state television. "Britain fails to win strong UN support in sailor row" read a rolling news banner on the television last night.

However, in the salons of north Tehran, some accuse their government of provoking confrontation. And one grocer, who did not want to be named, said: "Things can get out of control and end up hurting people."