A plot twist involving a cannabis joint smuggled inside the case of a school orchestra’s piccolo player is not the usual stuff of school plays.

But few such plays are custom-penned by Patrick Marber, the writer regularly praised as one of the new leading lights of British theatre.

“I’m very excited by the idea of a 1,000-seat auditorium packed with children performing shows written for them,” Mr Marber said. “You get inspired by children’s enthusiasm. It was that, rather than an artistic impulse to write about adolescence, that made me write the play.”

His play, The Musicians, was written for the National Theatre’s Shell Connections youth festival, being held in July. Ten playwrights have contributed new, one-hour works to be performed by secondary pupils.

The Musicians tells the story of a school orchestra visiting Moscow for the European Festival of Youth. Their concert plans are thwarted when their instruments are impounded by customs officers after a spliff is discovered inside the piccolo.

All comes right in the end, however, in a conclusion that celebrates both the imagination and the unifying power of music. “I’m known for writing quite tough, bleak plays,” Mr Marber said.

“But I’m beginning to feel that a happy ending isn’t a crime. It’s a concession that art has different functions, one of which is to bring people together rather than just remind them of their aloneness. And I wanted something that one day my children could act in, and not think, ‘What a miserable bastard’.”

Having returned to school theatrically once, Mr Marber is now doing it again. He has been commissioned to write a screenplay based on Zo Heller’s novel, What Was She Thinking? The film, which will star Dame Judi Dench, examines the obsessive bond between two women teachers.

“School is one of life’s great universals,” he said. “We’re born, we go to school, if we’re lucky we fall in love, and we die.

“Children have the same problems: which tribe you belong to, who you are friends with, and who you are. You either spend the rest of your life getting over your school days or being who you are because of them.”

This reflection on youth marks a major change from his previous work. He first came to public prominence as one of the creators of Alan Partridge, and the news-satire programme, The Day Today. He later achieved critical acclaim with his stage work, including Dealer’s Choice, based on his experiences as a compulsive gambler. His best-known play, Closer, is a tale of sexual jealousy, renowned for its uncompromising succession of four-letter words.

But, as his two sons, both under three, approach school age, he has begun to think more about what he wants from their education. This, coupled with his forthcoming 40th birthday in September (“There’s nothing like staring down the barrel of 40 to make you think”) has led him to reflect on his own time at the independent St Paul’s school in London and Cranleigh, a Surrey boarding school.

“I hated school and I had quite liberal parents, so I did my A-levels at home alone. But I was probably formed as a writer at school, when I was 10 or 11. Behind every writer is a great English teacher. Mine, Richard Dawson, made us learn 10 new words before every lesson.

“I’m naturally rebellious, and naturally disposed towards controlling my own hours. It’s very important that I don’t have to be at work at a certain time. That’s why I hated school, and it’s why I became a playwright.”

Michael Rosen’s best teacher Friday magazine 4 www.shellconnections.org