The union urged the Government to recognise and plan for year-round pressures, and increase investment to target staffing levels, ambulance services and ward capacity.

UNISON national ambulance officer Sharan Bandesha said: ‘Using ambulances or corridors as makeshift treatment rooms is unacceptable and unsafe, especially when patients need urgent treatment.'

More than half (59%) of ambulance workers said the condition of patients worsened while in their care and over one in 30 (3%) reported people dying because they could not be handed to A&E departments quickly enough.

One in 14 (7%) reported caring for someone for 12 hours and more than one in eight (13%) said they had done this for six hours.

Nearly three quarters (74%) said they had waited in the back of an ambulance while queuing to hand over patients at A&E in the past 12 months and the same proportion waited in a corridor.

More than a quarter (26%) said vehicles were used as extra space for hospital staff to assess or care for patients during almost every shift.

Half (52%) had transferred patients to X-ray, CT scans or other tests and then returned them to the back of an ambulance.

More than four fifths (83%) believed handover delays were compromising the care and safety of patients, while seven in ten (69%) reported dignity and privacy being put at risk.

The majority (92%) of ambulance workers said they had finished late or their shift had overrun, followed by missed breaks (77%), being unable to eat or drink (65%) or go to the toilet (36%).  

More than half (57%) said their mental health had been affected. Of these, nearly one in six (17%) had taken time off work, one in 12 (8%) had sought counselling and one in 12 (8%) had been prescribed medication for their mental health.

More than a third (34%) were considering leaving their job because of the situation and almost three quarters (73%) were frustrated because the role wasn't what they expected.

A Department of Health and Social Care spokesperson said: 'Patients should not be left waiting in ambulances - this is unacceptable and we are taking urgent action to reduce handover delays and tackle corridor care.

'While last winter saw the best ambulance and A&E performance for almost half a decade, we know too many patients are still waiting too long. That's why expert NHS teams are supporting the areas facing the greatest pressure, alongside expanded urgent treatment centres and action to improve patient flow through hospitals.

'At the same time, we are helping more people get care in the community through improved access to GP and pharmacy services and mental health support closer to home, reducing avoidable pressure on emergency departments and helping patients get the right care faster.'