Record summer temperatures propelled UK excess deaths in people aged 65 and over to their highest level since records began in 2004, modelling from the UK Health Security Agency has indicated.
Excluding deaths where Covid-19 was the registered cause, the extra fatalities in this cohort across the five "heat periods" between mid-June and late August reached 2,803.
From July 17 to 20 this year when temperatures were at their highest and London was hotter than parts of Middle East, there were an estimated 1,012 excess deaths among over 65s.
"These estimates show clearly that high temperatures can be a fast and unsuspecting killer for those who are vulnerable," said Isabel Oliver, UKHSA chief scientific officer.
"Higher excess deaths occurred during the hottest days this year and a warming climate means we must adapt to living safely with hotter summers in the future.
"Prolonged periods of hot weather are a particular risk for elderly people, those with heart and lung conditions or people who are unable to keep themselves cool such as people with learning disabilities and Alzheimer's disease."
Heatwave in the UK - in pictures
Separate analysis from the UK's Office for National Statistics showed total deaths in both England and Wales reached 56,303, which was 3,271 above the long-term average.
Excess deaths were at their highest when temperatures peaked between July 10 and 25 when 2,227 fatalities occurred — 10.4 per cent above average.
There were 5,017 deaths above average among people aged 70 and over across the five heat periods, compared with 1,749 deaths below average in those younger than 70.
Each hot spell was followed by several days that saw a fall in deaths to below average, however.
This could mean that deaths among elderly and vulnerable people were "brought forward" by the heat and took place earlier than would otherwise have been the case.
"During the UK summer of record-breaking temperatures, there was an increase in deaths," said Sarah Caul, head of mortality analysis at the ONS. "However, these spikes around the hottest days were followed by periods of below average mortality."
"This is likely to be a result of short-term mortality displacement, especially among older age groups, where people died a few days or weeks earlier than expected.
"This trend is consistent with what we have seen in previous summers with heatwave periods.
"It is also the case that despite peaks in mortality during heatwaves, the majority of days in the winter period [December to March] show a higher number of deaths than we see during summer."
Heat periods are defined by the UKHSA and the ONS as days on which a level-three heat health alert is in place, or days when the mean temperature in central England is greater than 20°C.
The five periods meeting this criteria during summer 2022 were June 16 to 19, July 10 to 25, July 30 to August 5, August 8 to 17 and August 23 to 25.
Of the leading causes of excess deaths across the summer, those due to cardiac arrhythmias — an irregular heartbeat — showed the largest percentage change during the five heat periods.