The teenage daughter of the Marquess of Queensberry died from a drug overdose at a posh flat party, an inquest has heard.

Lady Beth Douglas, 18, the youngest daughter of the 12th Marquess of Queensberry, Lord David, died in March after taking cocaine and heroin at the flat.

Known to family and friends as Ling Ling she was the only daughter of Lord Queensberry's third wife, Taiwanese artist Hsueh-Chun Liao.

Westminster Coroner's Court heard that the student and talented violinist attended the party, in Notting Hill, with her boyfriend Jenan Karagoli who she sent out to get a bottle of wine.

When he returned, she was asleep on the sofa.

He carried on drinking and fell asleep next to her, but awoke in the early hours and couldn't rouse her.

Another partygoer told him she had taken heroin and he found injection marks on her arm.

The troubled teen died in March this year, just nine years after her half-brother Lord Milo Douglas threw himself from a tower block in Paddington .

Ling Ling's family history includes the marriage of her half-sister Lady Alice to Simon Melia, who she met at a prison she was holding a drama workshop at while he was serving nine years for armed robbery.

And the half-sister of another brother - Lord David's illegitimate son Ambrose Carey - married Salem Bin Laden, older brother of terrorist Osama. She married another Bin Laden brother, Khaled, when Salem died in a plane crash.

All the children are the descendants of another famous aristocrat, Lord Alfred Douglas, who hit the headlines as Oscar Wilde's lover in the 1890s.

Wilde took Lord Alfred's father, the 9th marquess of Queensberry, to court for libel and lost - leading to his eventual prosecution for indecency and fall from society.

The inquest heard that Ling Ling struggled with drug and alcohol addiction, and was being treated for a range of mental illnesses including bipolar disorder and emotionally unstable personality disorder.

She had been known by mental health services since the age of 13 because of her self harming and also spent time sectioned in a psychiatric hospital when she was 17.

Coroner Dr Shirley Radcliffe heard Ling Ling had been living with her boyfriend Mr Karagoli in north Kensington at the time of her death and was a student.

Mr Karagoli said the pair had been on a drug and alcohol binge in the two days leading up to her death and had attended a party in Pembridge Square on March 6.

He told the inquest he had been asked by Ling Ling to go out and buy a bottle of wine at around 8pm, and when he returned she was asleep on a sofa.

Mr Karagoli said he had fallen asleep himself but when he woke up at 1.30am found Ling Ling unresponsive. Emergency services were called but were unable to revive her.

It is believed she may have been dead for some time before her boyfriend tried to rouse her.

The distraught boyfriend said: "The day before she had asked me - spur of the moment and she knew she had leverage over me as I wanted to make her happy - she asked me 'where can we get some heroin? Because I want to try it'.

"I really didn't want to do it. She used to snort heroin back before I even knew her. I said I didn't know anyone.

"She made a phone call and said we were going to a party."

Mr Karagoli added she had not been taking her medication prior to her death.

A man and a woman at the flat brought cocaine for the party but there was no mention anyone was taking heroin.

He said: "They probably supplied the heroin and they probably gave it to her. I walked out and bought wine because we had some Cognac but Ling Ling didn't like to drink that straight.

"She asked me to get her a bottle of red wine. When I came back I saw the person who lived there in a chair with a crack pipe. Ling Ling was asleep on the couch."

The boyfriend said he had been taking Xanax, cocaine and drinking and fell asleep next to her. But when he woke up in the early hours he could not wake the teenager.

He added: "I couldn't wake her up. The man in the flat said she had taken heroin. I just picked up her arms and saw a little peck of dots."

The talented music student's mother did not attend the inquest into her death but father Lord Queensberry and half sister Lady Emma Douglas were present.

Lord Queensberry told the coroner: "There was mention there was a lot of drug taking in this flat. I was concerned because in this flat where my daughter died, it seems to have been connected with the injection of heroin.

"The owner of the flat is not here to make any statement. And the other people at the party, police haven't contacted them.

"I am almost certain that this is the first occasion in which my daughter, who had taken a lot of drugs, but she had not had intravenous heroin before as far as I know.

"No one takes their first intravenous injection of heroin without assistance. Someone helped her and nobody seems interested as to who that is."

The inquest heard the tenant of the Notting Hill flat, named as Gavin Brown, was excused from attending the inquest for medical reasons.

It was said Mr Brown is "known to police" for allowing people to take drugs in his flat and is a vulnerable person.

A toxicology report found heroin, cocaine and morphine in Ling Ling’s blood. A hair sample also revealed she had been heavily abusing MDMA in the months leading up to her death.

The inquest heard Ling Ling underwent a mental health assessment in February, just a month before she died, but was not deemed to be detainable under the Mental Health Act.

Ling Ling's mother is said to have told the team she believed her daughter's mental health had been better recently.

One of the mental health assessors, Brian Rafferty, told the inquest: "We were looking in fresh to this assessment, we had got information but we had to take the assessment on that day. What we saw that day and what we heard from Miss Douglas' mother.

"That's the assessment and how it goes. It's a picture on that day."

Ling Ling’s cause of death was recorded as a cardiac respiratory failure and cocaine and heroin poisoning.

Recording a narrative verdict, Dr Radcliffe said: "Miss Douglas had a long history of mental health problems including a diagnosis of anorexia, bipolar disorder, emotional instability personality disorder and a long history of chronic substance abuse.

"Miss Douglas was clearly an intelligent and articulate individual but very difficult to engage with psychiatric services.

"There’s clear evidence to indicate the use of ecstasy, cocaine, heroin and codeine by Miss Douglas in the six months prior to her death.

"In the few days before her death Miss Douglas and her boyfriend had been staying in different hotels every night in the Queensway area and Mr Karagoki told us he was also taking Xanax a major tranquilliser."