More than 1.4 million people in South Yorkshire are waking up to tighter restrictions.
Tier three measures came into effect at midnight affecting areas including Doncaster, Rotherham and Sheffield.
Some 7.3 million people are now living under England’s tightest restrictions.
Meanwhile, Wales entered the first full day of a “firebreak” lockdown as police confirmed border patrols will attempt to block non-essential travel.
Gloucestershire Constabulary said it will patrol routes into the Forest of Dean area and pull over vehicles suspected of making unnecessary journeys out of Wales.
Drivers without a valid excuse will be advised to turn around and, if they do not, will be reported to police in Wales who can issue fines, the force added.