Fourth quarter to Jan. 2 like-for-like sales at Greggs' company managed stores averaged 81.1% of the equivalent 2019 level - an improvement from 71.2% in its third quarter.

However, Chief Executive Roger Whiteside said the new lockdowns would stall that recovery.

"I would imagine that sales would fall back down again," he told Reuters.

"The difference between November's lockdown (in England) and this lockdown is the schools are closed, so there's no reason to leave the house to take the children to school. That's a further tranche of footfall that is lost," he said.

He added that it was impossible to predict if Greggs will return to profit in 2021.

(Reporting by James Davey, editing by Estelle Shirbon)