An investigative journalist’s charity was made a school’s cause of the year by teenagers on a mission to raise awareness of the prevalence of mental illness at girls schools and among young people.

Three pupils at all-girls Channing School, in Highgate, bid for their school to raise funds over the next year for Sane, the mental health charity founded by Highgate philanthropist and campaigning writer Marjorie Wallace.

They chose the charity by chance before discovering that Ms Wallace lives only a stone’s throw away from their school in The Bank, and that her 28-year-old daughter is a former Channing pupil.

“It was a lucky coincidence,” said Molly Townshend, 17, who is one of the school’s charity officers.

“We think mental health is a really important issue in society and we wanted to raise awareness because we have never chosen a mental health charity before at Channing,” the pupil, of Cromwell Avenue, Highgate, added.

Classmate Tara Skok, 17, of Hampstead Lane, Highgate, said: “It’s quite well-known as an issue at all-girls schools, so we thought maybe we should be bringing that to light.”

Fellow charity officer Sophie Leigh, 17, added: “It’s a bit of a stereotype, but it’s because girls are so similar and over-analytical, in a very general way.

“They tend to over-think and so find it harder to talk openly to people.”

Although the girls hope to pull in thousands of pounds for Sane, their main aim is to raise awareness of the help available for young people who feel they have no one to turn to.

A statue of black dog “Horace” will stand outside the school hall to highlight the charity’s Black Dog campaign to reduce the stigma surrounding mental illness.

The girls will also lead the school’s hundreds of pupils in holding cake sales, fairs, and concerts over the course of the next academic year.

One in 10 young people experience a mental health problem which, if left untreated, can continue into adulthood.

Sophie, of Finchley, said: “It’s quite a hard thing to talk about, and quite taboo.

“The most important thing is, we hope, that at school we try quite hard to have an open, accessible environment and to always have someone to talk to.

“To know that people have someone to talk to is really important at all-girls schools.”

Molly added: “I don’t think a lot of people understand completely what mental health is, so we thought we would raise awareness.”

Sane chief executive Ms Wallace said: “I am thrilled that Channing School, where my daughter Sophia – now a music agent in Los Angeles – spent many rewarding years, has chosen Sane as its charity of the year.

“And I’m particularly pleased that they have brought our black dog ‘Horace’ to Highgate.

“What our Black Dog Campaign seems to have achieved is liberating the language of mental health so that young people can talk more openly and seek help more easily.”

To find out more about the work and campaigns of Sane, visit sane.org.uk