A property tycoon's daughter left traumatised after killing a teenage cyclist in Byfleet died from an overdose of heroin laced with a powerful painkiller bought on the dark web.

Then Putney woman Hannah James, 37, was found dead in the bath at her Paris home after injecting herself with the drug adulterated with fentanyl - a synthetic opioid 100 times more potent than morphine.

The daughter of a multi-million pound property developer had struggled with drug abuse since her teens, but was rocked by the fatal accident in 2011 and the breakdown of her marriage three years later.

Interior designer Hannah was sentenced to 100 hours of unpaid work for mowing down student Joel Semmens two days before his 18th birthday in October 2010.

The designer was charged with failing to stop after an accident and driving with an unsuitable tyre after blood tests showed she was not under the influence of drink or drugs.

Her father David said although he and his wife guessed their daughter may be struggling after the accident and divorce, they did not know about the drug addiction.

Westminster Coroners' Court heard Hannah had previously handed them an envelope to open 'in case something happened to her'.

It contained seven resuscitation orders from paramedics in 2014 and 2015 following a 999 call by her ex-husband to reported drug overdoses.

Speaking at the inquest, Mr James said: "In late October 2011 Hannah had a driving accident while driving away from a meeting with a client and hit and killed a cyclist aged 17.

"He was crossing the main road without stopping, on an unlit bike wearing dark clothing and no safety gear.

"She was charged that evening with dangerous driving under the influence of alcohol and drugs but blood tests proved she was not.

"She was traumatised by the accident. We noticed she was showing signs of depression and noticeably drinking more and, now we know, taking drugs."

He added Hannah was the youngest of their three children, born into wealth but was a troubled teenager.

He said: "Despite being expelled from school at 15, having bragged about taking drugs, she was a delightful child with an open and friendly manner.

"She was kind and generous and wished to help others less fortunate than herself.

"In 2000 the James family trust was set up with our children as the beneficiaries with us as the trustees.

"The children would be paid shared dividends and loan interests - which gave Hannah a large annual income."