Thousands of anti-lockdown protesters marched in central London on Saturday, as a senior UK scientist gave a warning that it was “a critical time” for the country, with its healthcare system under strain from soaring Covid-19 cases. Demonstrators carried banners bearing messages "Covid1984" and "Flu d'etat", chanting "take your freedom back, take off your masks". They claimed that coronavirus restrictions were a threat to their civil rights. The Metropolitan Police said at least 10 people were arrested in the Stop the New Normal protest. It was the fourth anti-lockdown protest to take place in London since restrictions were imposed in March. “This protest is no longer exempt from the regulations and we are asking demonstrators to leave," the Met said on Twitter. Earlier, former British government scientific adviser Prof Neil Ferguson said the country's coronavirus situation was worrying. "If the rate of growth continues as it is, it means that in a month's time we will be above that peak level in March and that is probably unsustainable," he said on BBC Radio 4's <em>Today</em> programme. "We are in a critical time right now. The health system will not be able to cope with this rate of growth for much longer.” He said ministers may be forced to close schools to older children in the run up to Christmas if virus cases continued to soar. The UK recorded 23,012 new cases of Covid-19 on Saturday, taking the country's tally to 854,010. The British Health Ministry recorded another 174 deaths, bringing the total to 44,745. Britain is facing a surge of Covid-19 patients in its hospitals, with 7,850 overall as of Saturday. This number includes 743 in ventilator beds. On Saturday, 1,139 more patients were admitted to British hospitals. "If we go beyond that there is a limit to what we can do in terms of reducing contacts, short of starting to target, for instance, the older years in schools and sixth form colleges where we know older teenagers are able to transmit as adults," Prof Ferguson said. "Of course, nobody wants to start moving to virtual education and closing schools even partially. "The challenge may be that we are not able to get on top of the transmission otherwise."