Jane Longhurst may have died instantly from a rare effect of strangulation.

The evidence given at court yesterday came with a warning to people who wear neck ties - don't have them too tight.

Home Office pathologist Richard Shepperd said: "There are significant risks when external pressure is applied anywhere in the neck."

Dr Shepperd said he believed Miss Longhurst died when nerves in the neck, which regulate blood pressure, were squeezed. Pressing them can send signals to the brain and stop the heart, causing instant death.

Graham Coutts, a 35-year-old guitarist denies murdering Miss Longhurst. He says the two were having consensual strangulation sex when Miss Longhurst, 31, suddenly collapsed dead.

John Kelsey-Fry QC, prosecuting, asked Dr Shepperd: "I wear a tie, am I at risk?"

Dr Shepperd said pressure anywhere on the neck was potentially dangerous.

His evidence was in contrast to that of another Home Office pathologist, Dr Vesna Djurovic. She earlier told Lewes Crown Court that death was probably caused by obstruction to the airway or starvation of blood to the brain.

Miss Longhurst would have struggled for several seconds before passing out and death would have occurred two to three minutes later.

These were the more common ways strangulation victims die and Dr Shepperd agreed the nerve pressure effect was rare.

Coutts is accused of strangling her at his flat in Waterloo Street, Hove, hiding her body for five weeks and then burning it in woodland near Pulborough.

Coutts, who downloaded thousands of computer images showing strangulation and violent sex, said the death was an accident. He admitted hiding the body and said it was to avoid causing shock to his partner, who was pregnant with twins at the time.

The prosecution claims he murdered Miss Longhurst to satisfy his perverted sexual fantasies.

Miss Longhurst was strangled with a pair of tights stretched tight round her neck when her body was discovered.

Yesterday, day nine of the trial, the jury heard from textile expert Julian Ellis who conducted experiments with tights.

He concluded that indentations found round Miss Longhurst's neck had been exaggerated by the tights trying to spring back into their natural shape.

Witnesses have paid tribute to Miss Longhurst, describing her as a brilliant musician, dedicated and bubbly.

But she was not always content with her life, according to witnesses whose statements were read to court.

Miss Longhurst, who lived with her partner Malcolm Sentance in Shaftesbury Road, Brighton, was often cross with him.

On one occasion she confided to a friend that he was annoying her.

Tanya Clark, a teacher at Uplands School for children with learning difficulties in Brighton, where Miss Longhurst taught, described her as a "caring, happy" person.

Ms Clark met Mr Sentance and found him nice. She said conversations with Miss Longhurst suggested Mr Sentance was worried about his job as an education welfare officer.

Miss Longhurst told her: "He's bugging me at the moment."

Miss Longhurst, she said, appeared unhappy about her partner feeling down.

Julie Carrett, a friend, said Miss Longhurst was a "trusting and caring" person but she had mentioned her partner was suffering stress.

She said pressure was taking up a lot of Mr Sentance's time while Miss Longhurst was wanting attention.

She said she felt concern for Miss Longhurst.

Karin May, another Uplands teacher, said Miss Longhurst was helpful, supportive, keen and dedicated.

One day, however, Miss Longhurst wept openly in class when an instrument was broken by a pupil who had been "grounding" her down.

Ms May said: "She was an emotional person and never tried to hide that fact."

Miss Longhurst occasionally spoke about her partner: "I got the impression Jane could be frustrated with Malcolm.

"He was unemployed for a while and was annoyed because she was working.

"Jane would moan and swear and said that they would even argue about who would cook dinner."

The situation changed when Mr Sentance found work as an education welfare officer.

But she was annoyed he had no time for her: "She did not seem to want to go home as much, she said he really needed help."

Ms May said they once arranged to meet in a pub and while Miss Longhurst showed up, Mr Sentance failed to, which annoyed Jane. On another occasion Miss Longhurst reserved tickets for a concert and Mr Sentance again did not show.

But Ms May said there was never any suggestion Mr Sentance was aggressive towards her: "They had their arguments but there was no violence."

The defence was expected to conclude its case when the trial resumes today.