Every week thousands of emergency calls are taking ambulance crews over an hour to reach, a BBC investigation shows.
The delays – affecting one in 16 calls in England for conditions such as strokes, heart attacks and fits – are putting lives at risk, experts say.
It amounts to over 4,000 “unacceptably” long waits a week for the second-highest category 999 calls. Wales also reported significant problems.
NHS bosses blamed rising demand and delays handing over patients at A&E.
Many ambulance services have increased staffing – only to find the extra resource largely being swallowed up by the rise in delays faced by crews queuing outside hospitals.
This has meant they have had to prioritise the most serious immediately life-threatening cases, such as cardiac arrests.
But these represent just a small