Iranian officials love bashing Britain but are notoriously thin-skinned when "perfidious Albion" - also known as "the little Satan" and the "colonial old fox" - dares to criticise the Islamic Republic.
So Britain's ambassador to Tehran, Simon Gass, must have known he would face a fusillade of outrage when he criticised his host country's human-rights record in a blog posting on his embassy's website.
Promptly demanding his expulsion, several hardline Iranian MPs publicly branded Mr Gass "insolent", "unethical" and "impudent". They lectured him on his purported shortcomings in the arts of diplomacy and declared him "persona non grata".
One MP, Kazem Jalali, said the Iranian parliament will discuss downgrading relations with Britain.
Tehran's fury comes after Mr Gass released a statement on International Human Rights Day last week declaring that nowhere in the world are journalists, lawyers and NGO activists under greater threat than in Iran.
He highlighted the case of a prominent human-rights lawyer, Nasrin Sotoudeh, who was arrested in September and is accused of acting against national security. Her real crime, the ambassador wrote, is "doing her job courageously and highlighting injustices that the Iranian regime would prefer to stay hidden".
Fortuitously, at least as Iranian officials see it, Mr Gass's website posting coincided with student protests in Britain over rises in university tuition fees. This gave Iran's outgoing foreign minister, Manouchehr Mottaki, the opportunity to accuse Britain of rank hypocrisy.
What he called the violent suppression of British student protests proved that the "so-called upholders of human rights and democracy cannot even tolerate the voice of peaceful protests from their intellectuals".
Mr Mottaki - who was unceremoniously sacked from his position by President Mahmoud Ahmadinejad yesterday - portrayed himself as all the more shocked and aggrieved because British police had "beaten" students on International Human Rights Day.
He warned that Iran was "diligently monitoring" the student protests. And he advised the British government to exercise self-restraint in the face of public demands raised by its own people.
Iran, Mr Gass might well point out, is in no position to chastise Britain on this score.
At least 100 Iranian students remain in jail following the huge, anti-government street demonstrations that convulsed Tehran in the wake of Mr Ahmadinejad's fiercely disputed re-election in June of last year.
Those protests were violently crushed. Thousands were arrested and scores killed, among them Neda Agha Soltan, a female student who instantly became a global icon of the opposition when her death was captured on a mobile-phone video.
Hundreds more students have been banned from continuing their education. By criticising the British authorities' handling of student protests, Iran only invites very unflattering comparisons to its own treatment of young dissidents, analysts said.
And, in contrast to the British media's wide coverage of last week's tuition fees protests, Iran's state-run media ignored nationwide student protests at home last Tuesday.
The annual commemoration of student political activism was used to voice opposition to Mr Ahmadinejad's government.
University campuses were ringed by riot police and about 100 plain-clothes militiamen while students chanted "death to the dictator".
Iranian parliamentarians have frequently demanded a downgrading of ties with Britain since the summer of 2009 when Iran's supreme leader, Ayatollah Ali Khamenei, accused the "evil British government" of fomenting the unrest that followed Mr Ahmadinejad's re-election.
There have also since been numerous protests outside Britain's embassy compound in central Iran, an oasis of pleasant green gardens in the dusty centre of Tehran.
The latest was on Sunday when hundreds of hardline militiamen burned the Union Flag outside the high-walled compound on Ferdowsi street.
They were responding to Iranian government accusations that Britain's MI6 intelligence agency, along with its American and Israeli counterparts, assassinated a top Iranian nuclear scientist last month.
Demonstrators denounced "the colonial old fox" Britain as Iran's "most evil enemy".
The Gass name has historic resonance in Iran. Sir Nevil Gass, the grandfather of Britain's current ambassador, was a high-ranking BP official who authored a key oil agreement with the Iranian government in 1949 that was rejected by the Iranian parliament.
Mr Resaie, the hardline Iranian parliamentarian, declared yesterday that the "sons of Great Khomeini [the ayatollah who spawned Iran's 1979 Islamic revolution] will slap Simon Gass in the mouth, just as they slapped his grandfather in the mouth".
Mr Resaie proclaimed that he was going to convince other MPs to "block the gates of this embassy with mud".