The figure could reach as high as 1.6 in the regions. The grave forecast came as the UK recorded 4,322 new cases, the highest daily increase since early May.
Twenty-seven further deaths were confirmed.
Yvonne Doyle, medical director at Public Health England, said: “We’re seeing clear signs this virus is now spreading widely across all age groups – and I am particularly worried by the increase in rates of admission to hospital and intensive care among older people. “This could be a warning of far worse things to come.
We must all play our part in controlling the virus by continuing to wash our hands, wear face coverings and follow social distancing rules.”
The latest survey from the Office for National Statistics estimated 6,000 people became infected daily in England in the week to September 10, compared with 3,200 per day in the previous week.
It suggested almost 60,000 people in the community had the virus that week, up from around 40,000 previously.
The ONS said there had been a marked increase in people testing positive in the age groups two to 11 years, 17 to 24, and 25 to 34.
Infection rates were particularly high in north-west England and in London, and were thought to be growing in all regions except south-west England and the West Midlands.
Meanwhile, scientists advising the Government warned of “widespread growth of the epidemic across the country”.
Sage said it was concerned cases may currently be doubling as quickly as every seven days nationally, with transmission rates potentially even faster in some areas of the country.
The group said: “It’s even more important for people to remain disciplined and adhere to the current rules.”
