The wife of ShelterBox founder Tom Henderson died from an overdose of morphine the day after her husband was sacked from the charity – leading to claims she had been “murdered” through stress, an inquest has heard.

Jane Henderson, 59, was found by her family at around 4pm on August 3, 2012 in the bedroom of the couple’s Helston home in Barbican Way.

It was widely believed at the time that Mrs Henderson had died from a heart attack, but a post-mortem carried out in the days following found high levels of morphine in her blood that were “suggestive of acute overdose just prior to her death.”

The inquest heard evidence that shortly after his mother was pronounced dead, the couple’s son John became extremely agitated, claiming to both police and ambulance staff that his mother had been “murdered” through stress.

He went on to tell police that they should arrest the chairman of ShelterBox trustees Ian Munday saying: “You’d better arrest him before I get to him.”

Mr Munday was subsequently given 999 advice by police as a precaution.

He was not called to give evidence at the inquest, nor was a statement read out.

Mr Munday has not responded to Packet requests for a response over the allegations.

Evidence from John Henderson said that his father Tom Henderson was sacked for gross misconduct in July 2012. He was initially offered a presidential role, which he accepted with certain conditions, but in a board meeting it was stated that he did not want it.

Earlier he had claimed that in recent years the charity had become “very corporate” and that senior management was “poorly staffed.”

During that time Mrs Henderson remained an employed member of staff, as a personal assistant to her husband and in other roles.

John said: “Mum was very aware of the problems in ShelterBox. It started to affect her greatly. ShelterBox’s problems made mum’s life up to her death intolerable.”

His father also stated: “She was under enormous stress and could not believe her friends and people we have known for many years could treat me in the way I had been treated.”

At 9.15pm on August 2, 2012 Tom Henderson received an email from Mr Munday telling him the offer of the presidential role had been withdrawn and he should not put himself forward as a representative of ShelterBox.

He said: “I made the fatal mistake of reading it out to Jane, who collapsed in front of me.”

Son John said: “When I arrived mum was on the floor pulling at her hair and screaming. I can only describe it as a mental breakdown.”

Trustee George Curnow was questioned by coroner Dr Emma Carlyon as to why neither he nor Mr Munday responded to telephone messages from Tom Henderson on the night the email was sent, asking for them to call him as it was “a matter of life and death.”

Mr Curnow said: “We discussed it amongst the trustees and decided it would be inappropriate for us to contact him. We tried to think of somebody else to refer to, to get in touch with him, and couldn’t think of anybody.”

He did not believe Mrs Henderson would have been “shocked or surprised” by the decision to withdraw the presidential role offer.

He agreed that Mrs Henderson would have lost her PA job as a result, although she had “other roles”.

Speaking directly to Tom Henderson, Mr Curnow added: “You have to believe that if I thought that [telephoning] would make a difference I would have responded as a person.

Mrs Henderson slept for an hour on the sitting room floor before being put to bed by her husband.

At 3am, however, she awoke to get a glass of water; that was the last time any of her family saw her alive, although they heard her snoring as late as 2pm the following day – two hours before she was found dead.

An open verdict was recorded by coroner Emma Carlyon, who said it was “not clear when and where the morphine was administered”.

No evidence was given to explain where it came from, with Mrs Henderson not being prescribed the drug since 2004, following an operation. She suffered daily pain from back problems and osteoporosis that led her to take other therapeutic drugs and sleeping tablets.

A spokesman for ShelterBox said in a statement: “Jane was a great friend to ShelterBox, and staff and supporters have fond memories of working with her.

“They will all wish to extend their deepest sympathies to those who knew her.”