Heaven knows what Archbishop Tenison would have made of it. His 17th-century portrait stares sternly down from the wall of his eponymous school’s hall as the six rappers from Saian Supa Crew put Year 10 French through their hip-hop paces.

In one corner of the room, Specta and Leeroy from France’s number one rap group coach 10 boys in a funk-driven rap about television culture. In another, Feniski and Vicelow are helping a group of enthusiastic 14-year-olds put together a rap about being too sick to go to school, while a third group, in the capable hands of Sly The Mic Buddha, is running through a number called “Daily Routine”. “Je me leve, je me leve,” they rap. “Je prends le p’tit dej, dej, dej.”

The Crew are dressed in the universal hip-hop uniform of baggy pants, big sneakers and baseball caps; the Archbishop Tenison boys are wearing ties and blue blazers. But the sense of identification between them is total. “Avec plus d’attitude,” Leeroy tells his charges. You’ve never seen a French lesson quite like it - and you’ve never seen a group of tough and streetwise inner-city children so keen to perfect their pronunciation and grammar of a complex foreign language.

“They’re not necessarily the most advanced group academically - and boys of this age tend not to express themselves as well as girls - so we wanted to find something that would motivate and enthuse them,” says Gemma Britton, head of French at the school in Lambeth, south London, which overlooks the Oval cricket ground. “I thought they would identify with rap. It’s a medium they understand and feel comfortable with. The way they’ve been listening to what Saian Supa Crew have been telling them is amazing - they’ve never listened to me that attentively.”

The lesson is part of a programme run by the Institut Francais in London called “Rap in Zep” - short for zone d’education prioritaire, the French equivalent of our education action zones. Funded by the French government, the institute has set up a music bureau under director Marie-Agnes Beau with a brief to use music to promote French culture in Britain.

“But we also wanted to do something useful and create an education programme,” explains Ms Beau. “The first suggestion was that we should take French singers into schools. But I didn’t think kids of today would necessarily connect with someone singing Edith Piaf songs. So I suggested rappers.”

France has the second biggest domestic rap market in the world after the United States. At home in Pais, Saian Supa Crew are superstars. But for this afternoon they’re surrogate French teachers. Like most French rappers, they have a very different attitude from their American counterparts, eschewing the gangsta poses and talk of “hos” and “bitches”.

Before the coaching session begins, they spend half an hour answering questions in French. They think Eminem is a good rapper but they disapprove of the way he promotes the use of drugs such as ecstasy. “Ce n’est pas bien,” Feniski says, as Sly The Mic Buddha gives a near-perfect one-man rendition of Eminem’s hit “The Real Slim Shady”, complete with vocalised beatbox and scratching effects.

The Crew are now experts in the classroom. Every time they play in Britain they do a school workshop or two; they’ve conducted sessions in inner-city schools in Manchester, Leeds and Bristol, as well as London. “We’ve targeted inner-city schools because they understand rap as an international street culture,” says Ms Beau. “Hip-hop allows inner-city youth to express their hopes and difficulties in a creative way, and it raises important issues of personal and social identity.”

Pupils prepared for the session by reading a biography of the group in French and listening to their music. “Then we spent a couple of lessons drawing up a list of questions for the interview,” says Gemma Britton. She also selected three topics - television, illness and daily routine - for the raps, which the boys work on with the group. The words of the rap are not written in advance but are added spontaneously from prepared vocabulary sheets.

“You can mix French words like you never thought you could,” says Perry Ramjohn, 14. “No matter what the language, you can always rap.”

Kyle Charalambous, also 14, and who turns out to be the most talented rapper in the class, is equally impressed. “It was a privilege to see how you can rap in other languages. And you don’t have to have all the bad language. They prove that rap doesn’t have to be violent and full of obscenities.”

It’s a high-octane afternoon and at the end of the two-hour session an exhausted Ms Britton slumps into an easy chair. “It was better than I dared hope,” she says. “You write down all the vocab and you wonder how it will work. Then, suddenly, from all four corners of the room, you hear the words and the rhythms and the beats all fitting together. They were listening and communicating back in return. It was a small miracle.”

Schools interested in participating in the French rap project can contact the French Music Bureau at 17 Queensbury Place, London SW7 2DT. Tel: 020 7838 2043 or fax: 020 7838 2119. Email: french.music@ambafrance.org.uk