Boris Johnson has insisted he can avoid imposing another England-wide lockdown this winter, describing it as a “nuclear deterrent” that he hopes never to use. Despite chief scientific adviser Patrick Vallance saying “national measures” might be necessary if there are fresh waves of the virus in the coming months, the prime minister said he “certainly” did not want to have to order the public to “stay at home” again. “I can’t abandon that tool any more than I would abandon a nuclear deterrent. But it is like a nuclear deterrent – I certainly don’t want to use it. And nor do I think we will be in that position again,” he told the Sunday Telegraph. “It’s not just that we’re getting much better at spotting the disease and isolating it locally, but we understand far more which groups it affects, how it works, how it’s transmitted, so the possibility of different types of segmentation, of enhanced shielding for particular groups, is now there.” The Department of Health and Social Care set out further details on Friday of how local lockdowns would work, including powers for local authorities to close individual businesses and outdoor spaces, and the ability of ministers to to step in and impose more draconian measures, including travel restrictions and “stay at home” orders. The prime minister’s confidence appeared to contrast with cautious remarks from Vallance in an evidence session with peers on Friday. “As you release measures, it is inevitable as you get more contacts that you will see more cases … Come winter, the challenges will be very much greater and of course there is a risk that this could need national measures,” Vallance said. He was was giving evidence at a House of Lords committee on Friday, alongside the chief medical officer for England, Chris Whitty, after the prime minister raised the prospect of a “significant return to normality” by Christmas. Vallance warned: “Everyone I’ve spoken to thinks it’s highly likely that this disease will continue to circulate and will come back in waves. And therefore the measures of reducing contact to reduce spread, the sorts of social distancing measures that we’ve talked about, and the hygiene measures that go along with that, will be necessary.” Dominic Raab, the foreign secretary, denied on Sunday there was any difference between Johnson and Vallance, telling Sophy Ridge on SkyNews: “National measures and national lockdown are the same thing.” He defended the prime minister’s upbeat message on Friday, saying it was important to give businesses and their staff “a sense of a target, and a sense of hope”. The UK’s national statistician, Prof Sir Ian Diamond, said on Sunday that he had not noticed any rise in coronavirus cases since the lockdown measures were eased. When asked if he had expected to see an increase in the number of infections as lockdown was lifted, he told Sophy Ridge that it depended on “how the population works”. He added: “The message has been quite consistent in that we must be alert and we must be socially distanced and if we are really super-careful and if we are able to follow all the rules it does seem to me that we should expect there to be a relative flatline at the moment … Clearly, over the autumn we will need to be ever vigilant.” In his Sunday Telegraph interview, the prime minister also criticised the civil service, saying he wanted to see more “confidence and belief” from Whitehall. Amid controversy over the shakeup being spearheaded by his chief adviser, Dominic Cummings, Johnson said: “I think the possibility of change really is there.” The prime minister also confirmed that he was planning an anti-obesity crackdown, but appeared to rule out increases in the sugar tax as part of the package of measures, expected to be announced this week. “On putting up prices of food for people who may not be on high incomes, I’m not instinctively in favour of that. There are other ways of doing it,” Johnson said, also saying he wanted to avoid “nannying” the public. “I think what people need to remember is that if you lose weight, you feel better, you really do feel better. It’s a psychological thing. It’s a mental boon, as well as greatly reducing your risk of all sorts of conditions, Covid being one of them,” he said.