The sharp rise in cases, released by Public Health England, has been triggered by a surge in two aggressive subtypes attacking the population simultaneously.
One includes the so-called 'Aussie flu', a strain of influenza A which wreaked havoc on hospitals in Australia during the country's winter.
The H3N2 subtype triggered two and a half times the normal number of cases in Australia. Britain's flu season tends to mirror what has happened there.
Experts fear the virulent flu strain, which has now reached the UK, could prove as deadly to humanity as the Hong Kong flu in 1968, which killed one million people. Usually, just one subtype, either influenza A or B, is responsible for the majority of cases. It spreads much easier in the cold weather.
But last week 522 cases of influenza A and 546 of influenza B were recorded across England and Wales. Some 43 cases are yet to be identified.
Some 23 people have died from the flu outbreak so far this winter, with nearly a third of fatalities having occurred last week.
However, this winter's outbreak shows no signs of slowing down, as flu cases are expected to rocket even further in the coming weeks. Cases this year are almost 10 times higher than they were at the same point in 2015, according to the PHE data. Just 132 cases were recorded then.
But in 2015, Government figures suggested that the winter flu played a part in more than 16,000 deaths. Only 577 deaths were recorded in the previous winter.
The total recorded in week 51 is also double that of last year, when 583 cases, mainly of the H3N2 subtype, were reported.
The sharp rise in flu is only expected to cause further problems for the NHS, with cases of the winter vomiting bug also continuing to soar.
Some 2,117 people have been infected with norovirus since July. The figure has raised at a steady level week-on-week since October.
Nick Phin, of PHE, said: 'Flu activity, as measured by a number of different systems, has continued to increase in the last week or two.
'This is to be expected as the season progresses and at this point the numbers are in-keeping with previous years.
'The circulating flu strains match those in the current flu vaccine, so the vaccine remains the best defence against the virus.'
The PHE figures follow repeated predictions by researchers that the flu vaccine may only be 20 per cent effective this winter - just like last year. Some experts in Australia blamed this as a reason why they suffered such a severe flu outbreak. The vaccine used in the UK will be very similar.
The WHO creates the vaccines in March, based on which flu strains they expected to be in circulation. They are then doled out in September.
Australia - whose winter occurs during the British summer - had one of its worst outbreaks on record, with two and a half times the normal number of cases. Some of the country's A&E units had 'standing room only' after being swamped by more than 100,000 cases of the H3N2 strain.
The elderly with their compromised immune systems are particularly susceptible, and a spike in cases among young children has also been shown.
The flu season in the UK and the rest of the Northern Hemisphere tends to mirror what has happened in Australia and the Southern Hemisphere.
The same strains of the virus will circulate north in time for the British flu season, which typically begins in November and lasts until March.
Flu viruses are constantly changing proteins on their surface to avoid detection by the body's immune system - making it more deadly.
This transformation is called an 'antigenic shift' if it's large enough, and can lead to a pandemic. This was responsible for the swine flu outbreak in 2009.
The Aussie flu is transforming quickly, but not fast enough for experts to describe it as a shift. However, it is slowly building up immunity.
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