A pensioner from Watford, who died suddenly and unexpectedly in November 2007, passed away from unknown natural causes, a coroner has ruled.

Marie Smith, 72, from Chester Road, suffered a number of health problems and was registered as blind. But following her death on November 9, 2007, a post mortem found no "unnatural" cause of death.

Rather than record an open verdict, Hertfordshire Coroner Edward Thomas ruled that she died from an unascertained natural disease at an inquest.

The inquest heard Mrs Smith took medication for anxiety and depression but was able to live independently in her own home. However, two GPs noticed a "sudden deterioration" in her wellbeing several days before her death.

Dr Rachel Tudberry, from Coach House Surgery in Watford, said: "She always dressed, washed and organised her meals. She seemed to stop doing that two or three days before dying. That was of some concern."

Following discussions to find her a bed in a respite home, an agency worker from Concept Care spent the night of November 8 with Mrs Smith.

Rita Anaba helped Mrs Smith light a cigarette, use the toilet and fetched a hot water bottle. She checked on her patient every hour, the last time at 5am. But around an hour later, when she was told by Mrs Smith's lodger that she was normally up by that time, the pair found she had passed away.

Dr Jeremy Shindler, also of Coach House Surgery, was informed Mrs Smith had died as the duty doctor on November 9. He said: "I saw someone who appeared to die peacefully. The most likely explanation was down to anxiety, rather than physical."

Elaine Rabbit, a former adult protection officer with Hertfordshire Police, investigated whether the correct care was given.

She told the inquest, held at Hatfield Coroner's Court, Concept Care would have expected a nightsitter to sit in the bedroom but that they accepted they didn't give these instructions to Ms Anaba.

Ms Rabbit added: "The set-up of the room meant there was not much room for Rita to sit. Concept Care do accept they didn't do an assessment beforehand (because of short notice)."

Dr Alan Rubin, a consultant pathologist for West Hertfordshire Hospital NHS Trust, said: "We can rule out any unnatural cause of death. Her heart has stopped beating but we really don't know the cause of death in this case."

Recording a verdict of unascertained natural disease, Hertfordshire Coroner Edward Thomas said: "This death was very sudden. She would have been in no pain. It would have just happened. Whether someone was in the room or not would have made no difference.

"I'm satisfied that there was no unnatural cause of death. Although I cannot say what the disease was that caused her death, I'm satisfied that she died of a natural disease and she died of natural causes."