In the year to August, more than 1.1million critically ill patients were left waiting for an ambulance longer than the target of eight minutes.
They included victims of cardiac arrests, strokes and road traffic accidents. Some had to wait for nearly two hours.
The NHS figures – the worst on record – were blamed on migration, the failure of GP services and a shortage of paramedics.
To make matters worse, ambulances are having to queue outside busy A&E units and so cannot respond to other 999 calls.
Separate figures today show almost 77,000 ambulances waited at least an hour outside casualty departments last year – twice as many as two years ago.
Paramedics are meant to arrive on the scene of ‘category A’ calls – the most serious – within eight minutes of being dispatched.
But a Daily Mail analysis of NHS England statistics shows that, in 12 months, they took longer than eight minutes in more than 1.1million category-A calls.
This means they were late in 35 per cent of the 3.18million of category-A calls. The figures show the extent to which the under-staffed ambulance service struggles to cope with the soaring numbers of 999 calls.
In January ambulances were late for 36 per cent of category-A calls compared with 32 per cent in January last year.
And in March they were too late for 42 per cent, while in March last year the figure was 30 per cent. In August, the most recent figures, targets were missed for 36 per cent of calls compared with 30 per cent for the same month last year.
The crisis is fuelled by unprecedented demand from the ageing population and patients who are not seriously ill but use ambulances like a taxi service.
Paramedics say they are increasingly called to patients with minor injuries or illnesses who have been unable to get hold of a GP.
Some reported pressure due to migrants who do not register with a surgery or do not know where their nearest walk-in centre is.
The ambulance service is also desperately short of paramedics with an estimated 12 per cent of posts vacant.
These factors mean fewer ambulances are ready to respond to serious 999 calls.
Meanwhile Freedom of Information responses from the ten English ambulance trusts reveal 76,725 ambulances had to wait at least an hour outside A&E in 2015/16.
This was up from 51,632 in 2014/15 and 28,162 in 2013/14.
Katherine Murphy, of the Patients Association, said the figures were ‘terrifying’. She said: ‘It is particularly concerning that thousands of sick patients are made to wait in ambulances outside A&E for more than an hour, as their condition may deteriorate in this time. You can only imagine the panic anyone would be in if this was you and your loved ones in an emergency situation.’
Sarah Carpenter of the Unite union, which represents paramedics, said the figures reveal a ‘catalogue of pain and suffering for patients’. She said: ‘Hardworking and dedicated ambulance staff and paramedics are being pushed to their limit of endurance – and beyond.’
And Labour’s health spokesman Jonathan Ashworth said: ‘For patients already in distress this absolutely will not do.’
In March, South Western Ambulance Service reported a small number of category-A patients waiting more than 108 minutes for a response. And last month another trust, South East Coast, wrote to GPs urging them not to call 999 from surgeries in a desperate bid to reduce demand.
The same organisation was last year found to have downgraded thousands of emergency calls in a bid to hit response targets.
Many trusts increasingly rely on firemen, the police or private ambulance crews to transport patients to hospital.
NHS England said the figures demonstrate the rise in demand. On ambulances waiting outside A&E, it said some had to delay handing over patients in order to continue giving care.
The Department of Health said: ‘We expect patient handovers from ambulance to A&E to happen within 30 minutes.
‘If delays occur, hospital and ambulance trusts must work closely together, with support from NHS England, to improve.’