The number of excess winter deaths in 2017 to 2018 was the highest recorded since winter 1975 to 1976, the Office for National Statistics (ONS) said.
There were an estimated 50,100 deaths above expected levels in England and Wales, the statistics agency announced on Friday.
Just one day during the last winter period – 25 March– did not record deaths higher than the five-year average, the ONS added.
Statisticians blamed the strength of flu last year, combined with lower effectiveness of the flu jab.
Nick Stripe, of the ONS, said: “The number of excess winter deaths in England and Wales in 2017 to 2018 was the highest recorded since the winter of 1975 to 1976.”
He added: “It is likely that last winter’s increase was due to the predominant strain of flu, the effectiveness of the influenza vaccine and below-average winter temperatures.”
Stripe said “peaks like these are not unusual,” with more than eight such spikes during the last 40 years.
The winter between 1975 and 1976 saw 58,100 additional deaths than expected.
Dr Veena Raleigh, senior fellow at The King’s Fund healthcare think tank, said: “These figures show the grim reality that many older people died in winter 2017/18 after a severe flu outbreak.
“Several European countries saw an increase in winter deaths in 2017/18, but the figures are particularly worrying for the UK which, after decades of progress, is seeing life expectancy improvements grind to a halt.
“This follows some other recent winters when seasonal deaths have been high. With an ageing population, the worry is that this could be the start of a trend of periodically high winter deaths.”
The ONS said that the main causes of the extra deaths last year were circulatory problems, dementia and Alzheimer’s.
But the most significant increase was for deaths caused by respiratory diseases, which peaked 85% when compared with non-winter months last year.
Colette Harris, deputy director of health advice at Asthma UK, said: “Cold air from plunging temperatures and flu are the top causes of asthma symptoms and we estimate flu could put four million people with asthma at risk of a life-threatening asthma attack this winter.”