Friday brunch at Yalumba restaurant is a boozy affair, with an open buffet featuring everything from the finest local lobster to chilled bottles of Taittinger champagne — all you can eat and drink for about £60.

The venue offers a snapshot of one of the many contradictions of living in Dubai: for native Muslims Friday is the holiest day of the week, reserved for family and prayer. For expatriates it is often a day of excess.

For Michelle Palmer these two sides of Dubai proved a toxic mix. The 36-year-old British publishing manager faces six years in jail after she was charged on Thursday with indecency in a public place, consuming alcohol and having an illicit affair with a British businessman, Vince Acors, 34.

The couple were arrested this month for allegedly having sex on a public beach after a day of drinking that began at Yalumba and ended in a white plastic lounge chair on Jumeirah beach.

Their case has captured headlines around the world, sensational for the severity of the potential punishment. For expats in Dubai it has simply highlighted the fine line defining life in the United Arab Emirates. Westerners are welcome as long as they do not flagrantly break the laws of the land, which are rooted in Sharia and laid down by the ruling Maktoum family of Dubai.

Given the rewards — tax-free living, sunny winters and a catapult up the career ladder — it is a sacrifice that Britons are willing to make in increasing numbers. The perks are part of the reason that much of public opinion has fallen firmly on the side of the authorities that arrested Ms Palmer and Mr Acors on June 5.

“Showing some respect to the local culture doesn’t mean you have to suddenly stop having fun. The UAE Government . . . are actually very easygoing with us, when you consider the rules in other countries. And when we do bend the rules, as long as we don’t rub their noses in it, they mostly turn a blind eye,” Claire Sharrock, a British writer, wrote in 7 Days, a popular Dubai daily.

However, as Dubai seeks to lure Westerners, its laws appear to be on a collision course with the values of some of the people it seeks to attract. Kissing in public and cross-dressing are forbidden. There is zero tolerance for possession of drugs or pornography. Homosexuality is banned. So is sex outside marriage.

For years expats have found ways around the strict laws. Unmarried couples who live together present forged marriage certificates to their landlords. Those without an alcohol licence buy drink through friends. Prostitution is an open secret.

However, the era of turning a blind eye is coming to an end. Undercover police now patrol Dubai’s most popular beaches, shopping malls and Friday brunches. Decency police have arrested nearly 200 people in recent weeks on charges ranging from cross-dressing to topless sunbathing.

Yesterday Lester Waters and Glen Whittingham, who arrived from London last week on a construction contract, went for a swim on Jumeirah beach and described the atmosphere as oppressive. “The undercover police patrols are a bit underhanded,” Mr Whittingham, 48, from Birmingham, said. He also thought that some were particularly harsh towards women. Other expats, particularly those who have lived here for a long time, dismiss such sentiments as “newcomer’s naivety”.

Mark Denton, a TV executive from Manchester, moved to Dubai seven years ago from Singapore. “This isn’t London or Ibiza or Singapore. If you don’t like the aspects of life that impinge on your civil liberties then you can leave,” he said.

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