Cressida Bonas
Cressida Bonas at England's Six Nations international rugby union match against Wales at Twickenham in London, 9 March 2014REUTERS/Stefan Wermuth

The 76-year-old stepfather of Prince Harry's girlfriend Cressida Bonas died after overdosing on prescription drugs, a toxicology report has revealed.

Former merchant banker Christopher Shaw was the fourth husband of Cressida Bonas's mother, Lady Mary Gaye Curzon.

He reportedly played a major part in her upbringing until she was 11, before the couple split after a four-year marriage.

Shaw died suddenly, only weeks after celebrating his birthday on New Year's Day.

An inquest in Salisbury, Wiltshire, heard that he was found dead in the bedroom of his rented home in The Close, near Salisbury Cathedral in Wiltshire, by housekeeper Nicola Smith.

Last month 24-year-old dance graduate Cressida was pictured arm-in-arm with her half-brother Jacobi Anstruther-Gough-Calthorpe at Shaw's funeral at Hinton Ampner Church in Hampshire.

The son of a country parson and a former head boy at Eton, father-of-three Shaw lived with Mary Gaye at the sprawling National Trust mansion Hinton Ampner in Hampshire, where he entertained in style with eight servants and five gardeners.

Guests at his parties included Sir Richard Branson and Rupert Murdoch.

Shaw was married first to banker Loel Guinness's niece Liza Gard, then to a Frenchwoman, and fell for thrice-married Mary Gaye in 1994. They were together for six years, and married for four.

Wiltshire Coroner David Ridley adjourned the inquest to a date to be fixed.

After Shaw's body was found in January, Ridley ordered an investigation into his death. It had been thought he may have died from natural causes.

But the inquest was eventually ordered several weeks later because his death was "unnatural".