Stringent Islamic laws have now ensured that even the traditional five day pilgrimage at Chak Chak in the central Iranian desert is not left untouched.
The biggest annual event in the Zoroastrian calendar, it involves thousands of candle-bearing pilgrims paying homage at the shrine where 'Nikbanou, the daughter of the country's last Zoroastrian monarch, King Yazdgerd III, is said to have sought refuge in 652AD from the Arab conquerors who brought Islam to Iran,' says the report by Robert Tait.
But the 'boisterous scenes of wine, unveiled women and song' which 'confounded the popular stereotype of religious worship in contemporary Iran' ended when the government VIPs arrived.
'Lighting candles in line with the Zoroastrian belief that fire symbolises God's light, they worshipped the credo of "good thoughts, good speech, good deeds" which the faith's founding prophet, Zoroaster - also known as Zarathustra - propounded at least 3,000 years ago. They also conversed noisily in a pre-Islamic form of Persian stripped of the modern Arabic loan words used by their Muslim compatriots,' the article said.
'But the sense of refuge worshippers traditionally enjoy was tested by the unprecedented government attention paid to this year's event, in the form of a visiting delegation sent by President Mahmoud Ahmadinejad, along with interior and culture ministry officials.'
The mood changed instantly, with women covering their heads and the men becoming less voluble.
"This is the only time during the year when we are allowed to do what we want, but even here they don't leave us alone," the article quoted Giti, 55, as saying as she reluctantly put on her headscarf.
But Kourash Niknam, the sole Zoroastrian MP in Iran's parliament, believes that the gesture was voluntary. "We just wanted to show respect because it is they who rule and we are living in their community," the Guardian quoted him as saying.
Many Zoroastrians fled to India --where they are know as Parsis--to escape the Arab invasion of the sixth and seventh century.
Some 25,000 Zoroastrians live in Iran, and though officially they -- along with Jews and Armenian and Assyrian Christians -- are a constitutionally protected religious minority with guaranteed parliamentary representation, complaints of discrimination are widespread, the article says.
Access to high-level posts in the government and armed forces is blocked, and some Zoroastrians say they are pressured to change their religion, it says.
'A law awarding Zoroastrians who convert to Islam their entire families' inheritance at the expense of non-converted relatives has caused misery and bitter resentment. Despite legislation decreeing that all religions are entitled to equal blood money (compensation) awards, Zoroastrians say that, in reality, they still receive only half the sums given to Muslims,' the article says.
"We don't have the right to make programmes about our religion," complained Mr Niknam. "I have no platform on radio or television to go and speak about Zoroastrianism. We cannot get any budget for building a new fire temple when mosques are being built one after another."
But despite this, many Zoroastrians say they are better treated now than they were under the last Shah, Mohammed Reza Pahlavi, says the article.
Apart from a decline in religious prejudice among younger Muslims in Iran, they believe that the uniform dress code imposed by the 1979 Islamic revolution has made a difference.
"Before the revolution, all Muslim women in my home town of Yazd wore chadors and only we Zoroastrians didn't," the Guardian article quoted Goharbanoo, 40, as saying.
"The Friday prayer leader ruled that on Fridays, Zoroastrian men had to wear white and women traditional clothes. It meant people could recognise us easily and they would be very rude to us. When we went into a grocer's shop, we wouldn't be allowed to touch the fruit. We even sat on separate benches at school and had separate drinking water. Thanks to the revolution, everyone dresses the same now. People back then were more religious. Today's generation is ashamed of the prejudice of their ancestors."
The article concludes by noting that 'some Zoroastrians have sought refugee status in America under an officially backed programme to help Iranian religious minorities.
'But Behzad, 31, an unemployed computer graduate who complained of being denied a gun during his national military service, rejected that option.'
"Why should we leave? This is our mother country," the article quoted him as saying. "Iranian culture is wonderful. Western culture is stress, stress, stress."