Despite concerns about COVID-19 ‘lockdown fatigue’ affecting compliance, most people adhered to the rules on intimate physical contact (ie, sex) between households. Four months after the first lockdown started, ~10% of survey participants in the Natsal-COVID wave 1 study reported sex outside the household in the 4 weeks prior to interview (quasi-representative web panel of 6654 British residents aged 18–59 years; July–August 2020).