Chinajan, from your link...
// However, Paul Hunter, Professor in Medicine, UEA, expressed some reservations about the study’s methodology. He warned that “any estimate of the size of the impact of eat out to help out on case numbers should be treated with some caution”. //
The study found a 8 to 17% increase in people who had visited a pub/restaurant. But that was in line with the general trend throughout the country in all sectors.