Just when Tony Blair attacked hardline Muslims for their “regressive” attitude to women last week, his wife awaited the law lords’ judgment on whether a girl she has represented should be allowed to attend school covered in full Islamic dress.

By ruling that her school was right to exclude her for refusing to wear uniform, the law lords effectively sided with Tony and against Cherie. And against Shabina Begum, 17 — partly because they feared that when the girl from Luton launched her campaign aged 13 she was being coerced into it by the kind of regressive Muslim forces Blair was worried about.

Over lunch with her after the judgment, which overturned a Court of Appeal ruling that had said Shabina could wear a jilbab to school, the impression that she was not acting of her own free will was reinforced. Interviewers are used to the odd minder guarding a star, but never an entourage as formidable as that surrounding this teenager.

There, by Shabina’s side as ever, is her elder brother and legal guardian Shuweb Rahman — a radical accused of “verging on the threatening” when he kicked off the dispute by demanding that Shabina be allowed to attend school in her favoured tent-like garment. Even my hardly racy request to sit next to Shabina at lunch so we can talk is greeted with glares.

As the mineral water flows I begin to wonder if it is less the “regressive” forces of Islam leading Shabina astray than the progressive forces of legal aid. Actually, her brother, 23, comes across as her meekest minder and certainly the most charming. It is her white guards who are the real frights. First up: her powerfully built “celebrity consultant” (really: I have her business card). If this man-munching reptile is alarming, the three dragons from the legal charity opposite breathe fire: “You can’t ask that,” they hiss. “Is that relevant?” Think Cherie without the charm. At times the only one not expressing opinions is poor Shabina, whose dreams of becoming a doctor have been hit by disappointing GCSE results following two years’ sulk leave from school.

The dragons roam the land, picking up cases for the Children’s Legal Centre and paying Cherie’s monster legal fees. I hope that the Charity Commission and the Legal Services Commission investigate whether fighting such a divisive case was a proper use of charitable and legal aid funds.

Anyway, to Shabina: she is — if I may venture this — attractive. Sure, she is dressed from head to toe in a jilbab, but this is fetching, even showy, with purple patterns, offset by a funky multi-coloured bag. “I go shopping a lot with friends and I love bags, shoes, girly stuff,” she smiles. As one of the dragons points out — without irony — “Shabina is British, you know.”

Indeed, but is she free to lead a British life or do those around her restrict her in the guise of Islam? Her brother — who denies being part of Hizb ut-Tahrir, the extremist group — and another cove went to Begum’s Denbigh high school to confront the deputy head about the uniform policy. The school’s attitude was not a Gallic-style “no religion please, we’re French”. The Muslim head, backed by Muslim leaders, allowed an Islamic uniform of tunic, headscarf and trousers, based on the shalwar kameez, which Shabina had worn without complaint. However, Rahman and his mucker declared this uniform now de trop “to us”, as the female form could be traced underneath.

Rahman denies he was aggressive. Curiously, the jilbab is worn mainly by Arab Muslims. Muslims of Asian origin — like this family from Bangladesh — tend to wear the shalwar kameez which satisfies Koranic demands of modest dress. So what is this dispute really about? “Our belief in our faith,” Shabina says, “is the one thing that makes sense of a world gone mad.” Blimey, is that Simon Heffer hiding under the jilbab? Begum, now an orphan, has had a hard life. Her father, once a headmaster in Bangladesh, died in 1992; in April 2003 her mother, who spoke no English, followed. And, if grief and teenage angst were not enough, Shabina has endured a three-year legal fight over her uniform. She was predicted straight “A” GCSEs but scraped passes after relying on notes borrowed from friends.

Although disappointed by last week’s judgment, she seems overwhelmingly relieved that it is all over. She signals that she wants to abandon the case despite earlier mutterings of appeals to the European Court. Was she coerced? “No. People say my brother forced me, but my sister is not orthodox: how come she has not been ‘forced’? I am an intelligent person: I know there are organisations that could help me if I were.” She says that it was during the school holidays that she studied her religion more deeply “and realised that to practise my religion I needed to wear the jilbab”.

However, the law lords made a distinction: the right to believe may be absolute, but the right to practise belief must be qualified by circumstance. I put this to her and she stares back for the first time — with a hint of fire hitherto hidden with that downward frown: “Islam is a complete way of life; it is not something you leave at home.” A good point, but if you are allowed to take your faith to school with your lunchbox, could a Rastafarian claim it essential to his religion to smoke skunk in home economics?

“I do understand uniforms are important,” she counters. “I was even happy to put the school logo on my jilbab. But smoking pot is illegal; wearing the clothes of your religion is not.” Hmm: a silky debater. But if schools declared that “anything goes” for religion, think of the ramifications. Tony Blair realised a Shabina victory would mean the end of uniforms. If Muslims are granted exemptions then the Vicky Pollards could argue for nose studs: at what point could a school say “enough”?

“If a practice such as an earring is against health and safety it should be banned, but if it is to do with a religion it should be allowed,” she says. But in a secular(ish) society that line is unsupportable. Shabina suggests that her school forced her out — she now attends a college where she can dress as she chooses — but the law lords affirmed that no school is obliged to take a pupil on that pupil’s terms. If Shabina could not abide by the rules, the onus was on her to find a more congenial school.