CALL centre staff took eight minutes to send an ambulance to a dying prisoner despite a prison officer's pleas, an inquest heard.
James Best collapsed in his Wandsworth prison cell on September 11, 2011, after exercising in the prison's gym.
He was awaiting sentencing for stealing a gingerbread man during that summer's riots in Croydon, where he had been living.
The 37-year-old was pronounced dead before paramedics reached him.
In a 13-minute 999 call played to the jury at Westminster Coroners' Court on Wednesday, prison officer Paul Morris was heard pleading for an ambulance for Mr Best, who was having "severe difficulty breathing".
But he was told "we may not be able to send you an ambulance immediately" based on the limited information he had provided, and because he was not a healthcare professional.
Mr Morris told the handler a trained nurse with Mr Best was "screaming on the radio" and asking for an ambulance. However, because Mr Morris was not able to respond to specific questions about Mr Best's condition, his answers were registered as "unknown" meaning the call was downgraded to a lower priority.
The call handler, who asked her manager for advice off tape, was finally told by Mr Morris that the man was "having a heart attack," and "this man is dying and we need an ambulance".
Asked by Westminster coroner Fiona Wilcox whether Mr Morris would have had more success in getting an ambulance had he lied, the call's handler, Lauren Hutson, replied: "With the way that the system worked at the time, yes."
Susan Watkins, London Ambulance Service operations manager for control services, said the call handler had been "proactive" in keeping the call open and turning to her manager, who kept an ambulance running while they worked out what was going on in Wandsworth.
She said: "The EMD's role is to be less emotive if you will and to take the information, because people will call up and ask for ambulances for all sorts of things and clearly it's a finite number of vehicles we have to prioritise."
The system has now changed, the court heard, so that clinicians are available to emergency dispatchers, and can take calls on behalf of healthcare professionals. Any 'code one' calls in prisons – the type made when Mr Best collapsed – will also trigger an ambulance being called.
The inquest was scheduled to finish today (Friday). Coroner Dr. Wilcox said she is dealing with five inquests that involve problems with London Ambulance Service's triage system.