Nationwide figures show the East Midlands Ambulance Service (EMAS) had the greatest number of long delays – one in eight calls (16.2 per cent) took over an hour.
The national average is 6.32 per cent.
Experts say the delays for ‘category 2’ 999 calls – meant to be reached in an average of 18 minutes – put lives at risk.
EMAS has defended its crews, saying they are working ‘harder than ever’, but added demand is at an all-time high.
EMAS points out delays are part of a wider issue with crews often kept waiting at hospitals because of delays in handing over patients.
Lincolnshire hospitals have some of the longest wait times in England.
Rachel Power, chief executive of the Patients’ Association, said people were being ‘let down badly at their moment of greatest need’ and added delays were ‘a matter of life or death.’
Ben Holdway, director of operations at EMAS, confirmed more staff and more vehicles were being used but the time they were ‘on the road’ was limited by hold-ups at hospitals. He said it was ‘clear’ the NHS needed more beds and a ‘well functioning’ social care system.