At just after 10 o'clock on Friday morning Maha al-Qahtani swapped places with her husband, Mohammed, and took the wheel of the family car.

For the next 50 minutes, she drove through the Saudi capital, along the six-lane King Fahd Road, through Cairo Square, down the upmarket Olaya Street with its shopping malls, Starbucks, Apple store and boutiques.

"No one tried to stop us. No one even looked," the 39-year-old civil servant said. "We drove past police cars but had no trouble."

In fact, the biggest problem for Qahtani was her husband sitting next to her in the family Hummer. "He kept telling me to slow down or speed up. He was very fussy," she said.

This is Saudi Arabia, the only country in the world that bans women from driving motor vehicles.

Qahtani was part of a small but striking movement of women determined to do something about it.

The exact number of Saudi women who protested was unclear. It was certainly not a mass movement.

By mid-afternoon a handful had driven in Riyadh, a few in the southern port city of Jeddah, a couple in Dammam in the east, perhaps 30 or 40 overall in a country with a population of 27 million including migrant labourers.

But it was a breakthrough. In the closed and authoritarian kingdom, such open and premeditated dissent is extremely rare. Under the spotlight of international attention, Saudi Arabia's rulers had clearly decided to allow the protest to go ahead.

"It is not the issue of women's driving itself which poses a problem, it is the challenge to authority," said a political analyst, Khaled al-Dhakil. "But … change is eroding that authority."

This was the closest Saudi Arabia has yet got to the revolutionary upheavals of the Arab spring. A "day of rage" declared in March was, outside areas dominated by the Shia minority, a non-event. A lack of tradition of public protest and heavy security presence rapidly ended any efforts at mobilisation.

Last month seven women were arrested for driving. Manal al-Sharif, a 32-year-old who had posted a video on the internet of herself at the wheel, was held for 10 days, made to sign a pledge not to drive again and banned from talking to the media.

On Friday, a different mood prevailed. Police appeared to be under orders not to intervene. In Jeddah, one woman said she had been detained by soldiers and escorted home. Others reported being ignored.

But when Qahtani, who holds American and international driving licenses, tried driving again in the afternoon, she was stopped after 30 minutes by police, given a ticket for driving without a Saudi licence, and sent home.

The question now is whether this signals forthcoming concessions from the authorities. King Abdullah, a relative moderate reigning since 2005, is known to be sympathetic but constrained by a conservative religious establishment.

The support of the clergy has been crucial to the house of Al Saud and successive kings have been careful not to antagonise them. Earlier this year, clerics issued a fatwa against challenging the royal family's authority.

Many clerics claim the driving ban prevents vice by stopping women interacting with male strangers – despite the enforced proximity with a hired driver.

Wajeha al-Huwaider, the activist who filmed Sharif's drive, said the "big campaign" might make the government rethink.

"Driving is a basic simple right. Denying it is hurting the image of the country. Even if the ban is nothing to do with religion, it is also hurting the image of Islam," she said.

Social networking sites such as Twitter and Facebook have been key for the women drivers, providing support networks and, crucially, publicity outside the kingdom.

The legal situation is unclear. Supporters say it is justified by both religious fatwas and the rulers' own statements. Critics say there is nothing in Islam to back the ban and that there has never been a royal decree.

Women in Saudi Arabia are also banned from voting or from leaving home without a male guardian.

Previous campaigns to overturn the ban have failed. One, in 1991, resulted in nearly 50 women who drove losing their jobs and being banned from foreign travel. The critical question now is broader public opinion. Those driving on Friday come from a small – if growing – element of Saudi society.

Saad, a 24-year-old engineer who recently returned from government-sponsored studies in the US, said that Saudis should "get over" the issue.

"There are much more important issues here than women driving. We need to be more broad-minded," he said.

But many others disagree. Abdullah al-Otaiba, who trades camels on the outskirts of Riyadh, said that women driving was a "bad idea".

"You have your ways of doing things in the west and that's fine for you. We are conservative people. We are not democratic. We have another religion and women should not go alone," he said.

There is room for compromise – the most likely outcome, experts says. Some younger clerics would accept women being allowed to drive in case of emergency.

The women, most of whom learned to drive overseas, say their campaign will continue until a royal decree is issued allowing them to drive "without any conditions".

"It's our right. We have to have it. We will continue until we can decide ourselves," said Maha al-Qahtani.

"I'm really excited," said Eman Nafjan, 32, who drove round her Riyadh neighbourhood for 15 minutes . "We need to do it again."

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