A patient might have 'frozen to death' 19 hours after an ambulance was first called for him, it has emerged.
The case - which happened in Lowestoft on 27 December - is one of 41 in the east of England highlighted to the BBC by an ambulance service whistleblower.
The leaked document lists patients who died or suffered harm over the Christmas and New Year period.
The East of England Ambulance Trust said it was formally investigating the patient's death.
The whistleblower's information comes in the wake of separate revelations from the Norwich South Labour MP Clive Lewis earlier this week that 20 people had died during delays in a 12-day period.
Commenting on the Lowestoft case, the ambulance service said police called in with concerns about a man who was sitting outside his home.
As he was breathing and conscious with "no obvious injuries", the service said it decided he did not need an ambulance.
A second call about the same man was made about 19 hours later by a third party who reported him not to be breathing and in cardiac arrest.
An ambulance arrived within eight minutes of that second call, the service said. The man was found to be dead.
The leaked document said the patient "appears to have frozen to death". The ambulance trust said it was not in a position to confirm the cause of death as that could only be done by a doctor or a coroner.
The BBC understands the patient involved was a man in his 50s.
Suffolk police has been approached for a comment on its involvement in the case.
Other cases revealed
All of the delays listed in the document sent to the BBC happened between 18 December and 3 January.
- The 17 cases listed in Essex include one in Benfleet in which a patient fell before going into cardiac arrest. The ambulance was delayed by more than six hours. The patient died
- In Chatteris, Cambridgeshire, a patient died on 27 December while waiting for an ambulance that took more than 13 hours to arrive
- A patient in Norwich waited more than seven hours after going into cardiac arrest. The patient died
- A patient in Bushey, Hertfordshire, died after going into cardiac arrest. The ambulance took 47 minutes to arrive
The trust said the decision had been made some time ago.
Mr Patten, who had served as medical director at the Luton and Dunstable Hospital, joined the board of the ambulance trust in July 2016.
A trust spokeswoman said: "The trust had plans in place however experienced extreme levels of demand over the new year period in particular.
"The trust was unable to respond to a very small number of the 50,000 calls we handled over a 15 day period as quickly as we would like.
"The trust is undertaking a rigorous analysis of that small proportion of calls. Where any suspected cases of potential harm are identified, then the trust will exercise its duty of candour to notify patients or their families."