More than half a million people spent 12 hours or more on a hospital trolley waiting for an NHS bed last year.
The waiting times are the worst since figures began, with 10 times as many people enduring the delay than did 10 years ago.
Policy experts warned the figures showed how bad things have got for emergency services.
Trolley waits occur when patients are left waiting for hospital beds after being admitted from A&E.
It often leaves patients to be treated - and in extreme cases dying - in hospital corridors.
In 2025 there were 554,018 people were left waiting for more than 12 hours - an increase of 36,000 (7%) on the year before.
Such figures were unheard of until very recently. Just 48,626 patients were waiting more than 12 hours in 2021.
Figures rose sharply in 2022 - due to a multitude of reasons, including the COVID pandemic and lack of resources.
Liberal Democrat leader Ed Davey MP branded the situation a "national emergency", and called for immediate plans to address the issue.
He said: "It's now confirmed in black and white.
"2025 confirmed as worst level of corridor care in NHS history, with over half a million people suffering degrading trolley waits in the last year alone.
"This deadly crisis is not what we expect from our NHS, and it's not what we pay our hard-earned money in taxes to fund our NHS for.
"Enough is enough. This is a national emergency, yet Labour ministers have allowed the crisis to get even worse. They must immediately implement our plan to end the A&E crisis once and for all.
"No government should tolerate this disaster, and ministers should be held legally accountable if they continue to fail in their duty to protect patients."
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Tim Gardner, assistant director of policy at the Health Foundation, said: "This is a grim milestone and a sign of just how bad things have got in our emergency services.
"Behind each statistic is a patient waiting unacceptably long for the care they need, with staff delivering care in impossible conditions.
"November saw a welcome fall in the waiting list for routine hospital treatment to 7.31 million and a substantial drop in the number of patients waiting over 52 weeks, despite industrial action by resident doctors.
"Nevertheless, the interim recovery targets set for March 2026 - a key marker of progress on the Government's pledge to restore the 18-week standard by 2029 - will remain difficult to meet."
The Department of Health has been approached for comment.
(c) Sky News 2026: Half a million patients left waiting on hospital trolleys for 12 hours or more
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