When no wounds or natural diseases were found in the body of a woman who died in her Watford home, doctors had to look for clues in her blood to piece together the mystery surrounding her sudden death.

A friend found Susan Tracey Armstrong dead in her Swanston House flat, in Whippendell Road, on September 22 last year.

An inquest held in Hatfield heard today heard how a post-mortem, carried out by pathologist Derreck Leitch, found no external or internal injuries, or obvious cause of death.

So blood tests were carried out, which revealed Ms Armstrong had taken cocaine and a combination of prescription medications - some of her own and some belonging a man called Gerald Gardner.

Ms Armstrong, 48, was born in Weybridge, Surrey and had a history of drug problems. She lived with and cared for the 70-year-old Mr Gardner, who she knew as "dad", but was of no relation.

The inquest heard how she and Mr Gardner were forced to sleep in separate beds in the living room of the one bedroom flat because there was an infestation in the bedroom.

On the night before she died, Ms Armstrong and her friend Dunice Fabray made dinner for Mr Gardner and sat down to watch Eastenders on television at 8pm.

After this, they put Mr Gardner to bed, cleaned the flat and then settled down to watch some more television, before going to bed themselves.

At 1pm the next day, Ms Fabray heard Mr Gardner call out for help because he needed to go to the toilet.

She found Ms Armstrong lying on the floor at an odd angle, with her face in a bag of laundry.

Edward Thomas said Ms Armstrong died an accidental death, caused by opiate, barbiturate and tricyclic antidepressant toxicity.

He added: "Ms Armstrong had been with friends and took a combination of medications, some not her own. None of the substances would cause death, it was the combination of them.

"She got out of bed feeling unwell, and then collapsed because her heart failed. She had a positive outlook and there was no suggestion she wanted to die."