A teenage ballerina was “brainwashed” by dangerous self-harm and suicide blogs before her death under a train at St Pancras International Station, her mother has said.

Fifteen-year-old Tallulah Wilson, known as Tootsie to her family, filled pages of her journals with the words “fat”, “ugly” and “worthless”, which she would then photograph and post on her online blog.

The West Hampstead schoolgirl died from head injuries after being hit by a train at St Pancras Station in October 2012.

Her mother Sarah said Tallulah had an “addiction” to a particular blogging website, where she created a fantasy account portraying herself as a cocaine-smoking anorexic. She would talk about suicide and post disturbing images of self-harm on her blog for her 18,000 followers.

Ms Wilson discovered Tallulah’s internet activity days before her death and contacted the website to have her account blocked.

“She said, mummy you don’t understand. I have 18,000 people who love me for who I am,” Ms Wilson told the jury at St Pancras Coroner’s Court on Monday.

“She went berserk. She was screaming, banging her head on the wall and pulling her hair. But I couldn’t let her carry on. She was brainwashed.”

Ms Wilson said she last saw Tallulah before she left the house with her grandfather for her GCSE dance class at The Place school in Euston.

Ms Wilson said: “I asked her, why haven’t you got your dance bag with you? You’re not dressed for class. She said, mummy I don’t need it today. I didn’t see her again.”

Tallulah, once headhunted by the Royal Ballet School, waved to 76-year-old Reginald Wilson from inside the dance school and he left after five minutes, happy in the knowledge that she was safe.

But she did not attend her class that day and CCTV showed her sitting on a train platform and jumping on to the tracks.

The inquest heard Tallulah was being treated by the Tavistock and Portman Trust in Belsize Lane, Belsize Park, for severe clinical depression from February 2012.

She was also admitted to the Royal Free Hospital, Hampstead, after she took an overdose two weeks prior to her death.

Ms Wilson said Tallulah became “obsessed” with the death of 15-year-old Rosie Whitaker, who went to the same dance school and jumped under a train in June 2012, even though the two girls had never met.

The inquest heard that church choir singer Tallulah was deeply affected by her grandmother’s death and had been allegedly bullied at St Marylebone Church of England School in Marylebone for years. She was taken out of school in May 2012 when a school nurse saw she had been cutting herself.

She then moved to the £11,000-a-year St Margaret’s School in Kidderpore Avenue, Hampstead in September.

Lindsay Anncock, head of inclusive education at St Marylebone and Tallulah’s mentor, said: “I really can’t say that she was being bullied. I’m absolutely sure they were unkind to each other but bullying is very specific, it’s persistent and it’s regular.”

The inquest continues.