A teenager found hanged in her room at a mental hospital has commited suicide even though “she was very happy”, an inquest heard.

Catherine Kay, 17, from Epsom, was found by nursing staff in her ensuite bathroom at Alpha Hospital, in Woking, in the morning of March 2, 2008, Woking Coroners’ Court heard.

She had arranged the pillows in her bed to look like a human shape the night before to fool nurses who did the nightwatch, so her absence would not be noticed.

A number of notebooks found in her room by police, containing cryptic messages, were taken to an expert in Aston University who deciphered them, revealing her plan to commit suicide on March 1.

Alpha Hospital mental health worker Slobodana Camber, the last person to see Miss Kay alive at the hospital, said the teenager seemed happy and relaxed and chatted with her until 11pm the night before she was found dead.

Mrs Camber said: “Catie was very happy and relaxed and she was telling me how many sweets she had that day and how she was feeling a bit hyper and then the alarm went off at 11am.

“I was standing in the corridor with Catie and the other girl and told them to go to their rooms.

"Catie rolled her eyes and said ‘oh, poor you’ because she knew sometimes it takes time to calm them down and she just went quietly to her room.”

Mrs Camber checked on Miss Kay throughout the night by looking through the glass on her door and said she did not notice anything unusual.

In the morning, two other workers, Lindsay Spencer and an assistant, found Miss Kay dead in her bathroom.

Since her death, the hospital has changed its patient watch system and made security improvements in all ensuite bathrooms.

Miss Kay had been receiving counselling from the age of 12 and had attempted to commit suicide twice in 2007, by taking a drugs overdose.

At the time said she even contemplated jumping from a bridge.

Her father, Ian, said at the court: “I believe I spoke to her last, on the phone, on Tuesday (February 26). She seemed distraught.

“She was telling me how she was being moved from the young people’s ward down to the challenging behaviour unit (CBU) on the lower floor because the hospital was carrying out building works.

“Catherine very much didn’t like being in the CBU because she was faced with more restrictive conditions and more rules than at the young people’s ward.

“She also asked me, she almost pleaded with me, to come home from the hospital that day and also if I could take her to the local supermarket because she loved cooking and she seemed to really enjoy spending time going round supermarkets looking to see what products they sell.”

He said he had to cancel the outing because the hospital said Miss Kay could not have any more leave, except for her Thursday evening dance classes.

It was said at the inquest Miss Kay had been upset about the fact she would have to leave the hospital when she turned 18, in October, and go into an adult care programme because she “did not want to leave her friends behind”.

She was described as a talented young woman, who behaved motherly towards the younger patients in the hospital and made many friends during her short stay.

Coroner Michael Burgess said: “This is one of these very sad cases, as I see all the time here, where a very disturbed young lady have sadly ended her life.

"Having read the diary she kept, she clearly had feelings that ran deeper than what she let others see.”

Coroner Mr Burgess recorded a verdict of suicide.

After the hearing, Alpha Hospitals released a statement, which read: “We have expressed our deepest condolences to Catherine’s family and have worked with them, the Coroner and with other agencies to understand what happened in this very sad case and to ensure that we learn any lessons from this difficult experience.

“Catherine was a popular patient at our adolescent unit at Alpha Hospital Woking and had appeared to be making good progress there.

“In the light of her progress, this tragedy was totally unexpected and was extremely distressing to the staff who cared for her at Alpha Hospital Woking.”