Prime Minister Boris Johnson said on Monday a new, more contagious variant of the coronavirus was spreading at great speed and immediate action was needed to slow it down.
The benchmark FTSE 100 index gained 0.4%, with general retailers and energy stocks gaining between 2% and 3%.
December was the busiest month ever for British supermarkets as tightening COVID-19 restrictions and the closure of restaurants, bars and cafes meant shoppers spent 11.7 billion pounds ($15.9 billion) on groceries, industry data showed.
UK Finance Minister Rishi Sunak’s plans to offer further help to businesses struggling under the renewed COVID-19 restrictions also aided sentiment.
The mid-cap index was up 0.1%.
Morrisons, Britain‘s fourth-largest supermarket group, gained 0.2% after reporting a rise in underlying sales in its latest trading period encompassing Christmas.