Three-quarters of coronavirus deaths in Britain might have been avoided if the lockdown had begun a week earlier, modelling suggests.
Researchers said that if the UK had imposed the measures seven days earlier its death toll now would be on a par with the 8,000 in Germany.
They also said it would have been possible to have a shorter and less economically damaging lockdown.
Britain introduced its lockdown measures on March 23, when 359 deaths had been reported. Germany took such steps on the same day, but had reported only 86 fatalities at that time.
The UK's death toll has now exceeded 35,000 people.
Modelling from British scientist James Annan suggests that entering lockdown a week earlier would have reduced the number of deaths by three-quarters.
Mr Annan, from Blueskiesresearch.org.uk, said an earlier lockdown would have been shorter and had less economic impact.
In a related blog, he wrote: "Implementing the lockdown one week earlier would have saved about 30,000 lives in the current wave (based on official numbers, which are themselves a substantial underestimate).
"It would also have made for a shorter, cheaper, less damaging lockdown in economic terms."
Modellers said the calculations showed that even small changes in the timing of interventions could make a significant difference.
Dr Kit Yates, senior lecturer in mathematical biology at the University of Bath, said: "In the early stages of an epidemic, the number of cases is growing exponentially. This means even a small change in the rate of spread or in the timing of interventions can make a big difference a short period of time down the line.
"It is clear that, had we locked down sooner, we would have reduced the spread earlier, limiting the number of cases and consequently the number of deaths.
"The other benefit of locking down earlier would have been bringing cases under control sooner and potentially allowing the release of lockdown sooner."
The modelling was revealed on Radio 4's More or Less programme, which highlighted differences in the testing regimes used by different countries earlier in the epidemic, with Germany carrying out 50,000 tests daily at a time when the UK could not even achieve that weekly.
As a result, at the point both countries entered lockdown, Germany had identified around 27,000 cases, when the UK had confirmed just 9,000, researchers said.