Boris Johnson warns tougher lockdown may be needed in letter to every UK household ‘We will not hesitate to go further if that is what the medical advice tells us we must do,’ says PM Peter Stubley. Boris Johnson is to write to every household in the UK urging people to remain at home “at this moment of national emergency” and warning that tougher lockdown measures may be needed to stop the spread of coronavirus. In his letter to the nation, the prime minister urges the public to obey social distancing restrictions to prevent the NHS from being overwhelmed by patients. Mr Johnson, who began self-isolating in Downing Street on Friday after testing positive for Covid-19, warns that “things will get worse before they get better”. The publicity campaign, which will be delivered to 30 million homes across the UK, is estimated to have cost £5.8m. “From the start, we have sought to put in the right measures at the right time,” the prime minister writes. “We will not hesitate to go further if that is what the scientific and medical advice tells us we must do.