The cause of the death of a woman at a Hampshire music festival should be revealed today.

A post mortem was due to take place into the death of a woman who collapsed at the Boomtown Fair near Winchester.

The 31-year-old was found unconscious in a toilet block at the festival on Saturday.

She is the third person to die at the festival in the past four years.

The four-day event |took place at Matterley Estate from Thursday to last night.

Medical and security staff at the festival were called to the toilet block at about 1.50pm on Saturday.

They found the woman unconscious inside, and treated her at the scene before she was taken to the Royal Hampshire County Hospital in Winchester.

But despite the best efforts of medical staff, she was pronounced dead soon after arriving.

The area around the toilet block was cordoned off while police investigated, but a spokesman said her death is not believed to be suspicious.

A Hampshire police spokesman said: “It is not believed to be suspicious and it is too early to speculate on cause of death and a post-mortem examination will be conducted in due course to help determine this.

“Police are providing support to her family including her husband who was at the festival with her.”

A spokesman for BoomTown Fair added: “BoomTown Fair would like to express our sincerest condolences to the family of the young woman who was found unconscious on site but despite the efforts of all our staff involved she was later pronounced dead shortly after arriving at Winchester Hospital.

“Our thoughts are with all her loved ones at this tragic time, and the festival is doing all it can to assist those involved.”

Last year 18-year-old Ellie Rowe, from Glastonbury in Somerset, died at the festival after taking the class C drug ketamine, most commonly used as a horse tranquiliser.

Police handed out leaflets to revellers at this year’s event with a stark warning from Ellie’s parents, to remind festival-goers of the consequences of taking drugs.

It reads: “Ellie Rowe was a bright, vibrant, wickedly funny, fun-loving young woman.

“On August 8, 2013, she went to BoomTown, high on excitement and anticipation – and returned home in a coffin.

“Before taking it, Ellie had drunk alcohol, which increases the poison levels of ketamine, and though her alcohol level was just a little over the drink-drive limit – she died.

“The effects of Ellie’s death will be life-long for all of us who knew her.

“It is too late for our beautiful daughter now, but we would ask anyone considering taking ketamine to think again.”

The leaflet also pictures the teenager, and explains that she was not a habitual user.

In 2011, 45-year-old Deborah Jeffery died from an Ecstasy overdose.

She suffered a heart attack as a result of taking the drug.

About 38,000 people |attended this year’s festival, which featured a wide range of musical acts including Shaggy, Ms Dynamite, The Wailers and Bellowhead.