A 45-year-old autistic man died after a short-staffed ambulance service took four hours to respond to his father’s 999 call, an inquest was told.

A controller told Adrian Sutton’s father a fast response vehicle was being sent to his son – but none arrived and it took another five 999 calls before paramedics turned up – by which time Mr Sutton had stopped breathing.

Mystery surrounded the death of the middle-aged man whose peculiar behaviour caused his dad to dial 999.

He was spotted bumping into furniture and speaking less than usual, and his worried father called at around 11pm.

After being told a rapid response vehicle would be sent for the 45-year-old, who had been diagnosed with autism, help failed to materialise, and elderly Peter Sutton rang 999 another five times – finally prompting a response when he told the operator his son was in cardiac arrest.

Mr Sutton died shortly after arriving at hospital.

Senior Coroner for Berkshire, Peter Bedford, said there were “missed opportunities” for Mr Sutton to have been taken to hospital but he could not say whether if he would have survived no clear cause of death was found.

However, a post-mortem examination carried out at the Royal Berkshire Hospital concluded that sudden arrhythmic death syndrome was the most likely cause of death.

An internal review was carried out by South Central Ambulance Service (SCAS) about the delay surrounding their response, which was seven times longer than it should have been.

The inquest heard the ambulance service was critically understaffed at the time due to sickness and people on holiday.

Reports from elderly Mr Sutton that his son had fallen down the stairs and hurt his arm failed to prompt questions about his condition worsening and should have alerted the operator, the report said.

Investigations manager for SCAS, Paul Cooke, said: “The ‘green’ response of 30 minutes was not achieved due to staff shortages and high call demand, the priority being ‘red’ calls.”

The coroner accepted that treating Mr Sutton’s symptoms as ‘green’ - meaning a half-hour wait – in the initial instance was acceptable but said his care should have been escalated as soon as his concerned father reported that he had fallen down the stairs.

Eventually Mr Sutton was whisked from his home in Norman Road, Caversham, to the hospital nearby where he died in the early hours of July 17, about four hours after the first phone call was made.

Mr Bedford said: “From the point of view of Mr Sutton’s family, I think the most difficult thing to accept is that a green triage of 30 minutes could have been explained and justified but you have put it at three-and-a-half hours until attendance, which is significantly more than 30 minutes.”

Widower Peter Sutton, whose wife died three years ago leaving him living with his son, recalled: “I said to him ‘have you eaten?’ and he said no, ‘have you had a cup of tea,’ no, ‘have you taken your tablets’, to which he said yes. He was falling about, he wouldn’t sit down.”

Mr Bedford said: “There was a shortage of ambulance crews at the time. There were missed opportunities to assess Mr Sutton face-to-face.”

“Because the cause of death has not been ascertained it was not clear whether earlier attendance would have effected the outcome.”

A narrative conclusion was recorded which stated that the cause of death was not ascertained at post-mortem examination but was most likely natural.